After Peggy gave birth, her partner’s ex suddenly turned up at their home.

At 32, Peggy Roddick found herself separated and in the dating world for the first time in her adult life.

Within six months, she met *Andrew on Tinder, and promptly fell into a relationship, moving in together a few months later, blending their family of five children.

"When we first met he didn't tell me a great deal about her," Roddick says of her partner's ex. "I knew they had separated after 15 years together. They had three kids, she had cheated on him and left him for someone else. He was scared to lose any time with his children who are his world."

On the surface, Andrew's relationship with his ex seemed okay, but things quickly unravelled after she realised he'd moved on.

"It was good while he jumped," Roddick says. "The second this stopped, and some boundaries were created, was the second the co-parenting relationship started falling apart, and she started to use the kids against him."

Watch: The signs you're with a toxic person. Post continues after video.

The downward spiral.

"The second I came into his life the games started," says Roddick. "From then on, she actively tried to separate us."

First, their photos together mysteriously vanished from his Facebook account. On Valentine's Day, her partner's ex sent him a string of emails — including a large selection of naked selfies.

"She had been trying to get him to leave me by telling him she wanted their family back together and sending nude photos to him," says Roddick.

She constantly lied about finances, frequently using Andrew's love for his children against him, demanding more and more money, without providing evidence for why.

"To be spiteful, she even took their son out of his soccer team — Andrew was the coach of the team and absolutely loved being a part of this with his son.

"I was never allowed at any training or games because it made her feel uncomfortable."

During COVID lockdowns, things went from bad to worse. Roddick was pregnant with the couple's first child together, and her 10-year-old daughter had respiratory issues, so she committed to financially supporting the entire household using her savings, to enable them to stay properly locked down.

Her partner's ex had other plans though, flouting the rules whenever she had the children in her care.

"Every handover was absolutely horrendous for me. Were the children going to bring COVID into our household and put my children's lives at risk? But each time, I had put my feelings aside because I couldn't bring myself to stop my partner [from] seeing his children.

"Every special occasion we had over the next three years was tainted by her, and our family was put in danger during COVID due to her reckless actions — but the final straw was when our daughter was born in 2022."

The psychological impact of a toxic ex.

Roddick's mental health rapidly declined as per partner's toxic ex continued to target them.

"I thought I was going insane," she says. "I was constantly triggered by everything around me. It felt like my only option to regain control of my life was to leave my partner. I really struggled with the options of protecting my sanity and losing him, or staying and living with the consequences of that."

About six months before their daughter was born, the pressure became too strong, and they decided to spend some time apart.

"We did live apart for six months to try to give us both some healing time but the thought of our daughter never knowing a life with her parents together was just heartbreaking.

"I think by having his eyes opened a bit to how controlled he was, he could set some firm boundaries that allowed us to continue our relationship."

Within two days of their daughter's birth, the incessant emails came flooding in. The ex also turned up unannounced, when she knew Roddick wasn't at home.

"With the history of her trying to come between us, this was obviously something that caused a great deal of distress and pushed me over the limit with my post-natal depression."

Ultimately, Roddick's partner had to give up 50/50 custody of his children.

"Unfortunately, as a result, he has lost all say in the children's upbringing — so everything he was worried about has eventuated, but we couldn't keep living like we were."

According to relationship counsellor, Susan De Campo, having a toxic ex has a devastating impact on individual mental health and new relationships.

"It creates hyper-vigilance. What's the next text/email going to say? Did my new partner ask the kids to empty their school bags — for the 5th time — too loudly? Will the kids tell my ex and am I going to get a solicitor's letter about him being abusive?

"[A] toxic ex can make you feel like they still control your life — and there is no escaping them. If it's not [the] issues with the kids, it’s [the] challenges to the child support agency, it's being inflexible about special events - 'no, I don't really care that it's your grandmother's funeral, it's MY weekend' or 'no, if the cruise gets back on Saturday morning, that's in breach of the orders, you can't go.' The intrusiveness on your life can feel overwhelming and end up making people feel helpless and hopeless."

De Campo says it can also impact new relationships — if you let it.

"It's like this looming black cloud that randomly appears to spoil your newfound happiness. There is also the potential that your new partner will question you — like, what does it say about her, that she was with someone like this — and had children with them? Which by the way, is really unfair — a lot of people don't discover certain aspects of their partner until after they have children."

Listen to Fill My Cup where Allira Potter shares how you can cut a toxic person out of your life in a way that is very... magical. Post continues after podcast.

De Campo says it's important to remind yourself that you can't control what you can't control.

"Remind yourself it's actually got nothing to do with you. Then, take a deep breath and do what is within your sphere of control."

De Campo's other tips for reducing the impact of a toxic ex include:

• Create boundaries up front and uphold them.
• Take the emotions out of co-parenting and keep all communication relevant to the children. 
• Keep records! something that may seem insignificant today may become part of the bigger picture later on and if done correctly can be relied on in court. 
• Look after your mental health! If you can't look after yourself, you won't be able to look after your children. 
• Create some space and ask a trusted person in your life to help you with communication whether it be for respite or just to keep all parties accountable for their actions.

Professional support can help, as can co-parenting apps which can help reduce the need for communication.

"The apps that cost something have better outcomes I think because you are literally investing in achieving a positive outcome. Some people have a separate email account purely for child(ren) related issues. They advise their ex that they will only check the emails every four days. If there is an emergency, then texting is the next option. In an extreme emergency, then a phone call is required. Setting these boundaries is really important."

At rock bottom, Roddick searched high and low for a co-parenting app to help ward off her partner's toxic ex, but couldn't find anything that effectively incorporated the step-parents — so she created her own.

"Co-parenting Plus creates a central platform for all communication which automatically records all communications for the use in family law proceedings," says Roddick.

"It takes away the emotion and creates a safe place to co-parent with no need for words. For example, instead of feeling like you are begging for money, you can simply upload the school newsletter, medical fees, etc.

"The other parent's rejection or acceptance is automatically recorded so there is no 'he said she said' and no disputes.

"You can request custody changes through the calendar, plan special occasions and extra-curricular activities knowing that if things don't go to plan, you have thorough records of what has transpired."

Importantly, the messaging feature is non-editable, unlike many other messaging apps that can be altered to show a different version of events to the court and are therefore not admissible.

"And finally, we allow the addition of support people for respite, transparency and accountability."

* Name has been changed to maintain privacy.

Feature image: Supplied.

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