Navigating a break up whilst still living together

Hi all,

Apologies if this is the wrong forum for this post. I feel I need a place to express my emotions in words and maybe get some thoughts on how to navigate day to day life.

Me and my now ex recently split up over the New Year and still live together due to finances.

To cut a long story short, we've been together almost 6 years on and off and have a child together who is 4. I myself have a porn addiction which traumatised my partner at the time and years of lying pushed her further and further away until she cheated on me with her best friend. She broke up with me afterwards and didn't tell me for at least 6 months of us being split, all during this time I found out that they'd been sleeping together during the period of us being broken up.

A few months passed and we were on better terms and decided to try again, although with a caveat, her best friend was still in the picture. In hindsight I was foolish to accept without completely being able to recover from the cheating and sleeping together which proved the downfall in our relationship again after being together for another year or so. Realising I wasn't able to put my all in to the relationship anymore because I was constantly living in fight or flight mode with him still in the picture. Self esteem was stripped away and I was constantly comparing myself to him anytime they were together and always feeling second best.

He's still her best friend and now we are not together, every opportunity she has is spent round his, staying round overnight whilst claiming nothing is going on between them (I find it hard to believe given the same response was given when they actually were sleeping together whilst we were broken up) and has been the catalyst for a lot of arguments.

We are onto present times and I'm mentally worn out, have I made the correct decision in us breaking up again or am I just in denial in thinking that I might have been wrong? AITA for not being able to move past the cheating and lying to spare my feelings when she forgave me for the betrayal and lying from my porn addiction or am I justified in thinking that cheating was a boundary too far and being unable to move past it with him still in the picture? Is she being cold in taking the opportunity to get away from the house and staying at his to "get away from reality" or am I wrong for feeling that it's an unfair thing to do?

I'm on the fence myself, we are not together and even though part of me knows that she has no obligation to me and how I feel about this situation anymore, the other part of me still feels it's a cold thing to do at the very least whilst we are still living together and feelings are still there, still making me feel like I'm stuck in that fight or flight mode and having my little self esteem constantly beaten down whilst still comparing myself to him?

How do I navigate this scenario without becoming overbearing in how I feel about what is going on?

Ideally I am going to move out in March time and there's a lot of emotions around that, leaving the woman I spent six years of my life with, leaving the family I've been a part of for the last 6 years and only being able to see my own son 1-3 times a week Vs seeing him daily. I'm struggling.