@ChaoticMum
Being cheated has been the most painful experience of my life with BPD.
I don't know you or the relationships so I can't offer specific advice, but I do completely understand some of the feelings of anger/fear/humiliations that you might have, and I can offer hope that you can, with support, time, and maybe some difficult choices, you don't have to experience them forever.
In my personal experience, I ended up remaining with my cheating partner because I had convinced my self no one else would accept me and that I couldn't love someone else the same way again. Turns out I was VERY wrong; but at the time it absolutely felt real. I only started to make a recovery after the relationship ended. It was way harder at first, but then became easier over time.
My point isn't that you and everyone else should seek separation after cheating - I think that completely depends on the relationship itself, what underlying feelings/circumstances are driving a desire to stay/leave, etc. But I can confirm that those emotions/fears that feel like they can never go away, can actually go away - and you may have more control than seems possible.
I wasn't aware of that control because I wasn't brave enough to make the hard decision I personally needed to make; I didn't choose to separate and face my fears of being alone on my own accord. That partner left me. But I'm glad they did because it was only then that I started feeling better and moving on. Now I think I could see that partner in the street and think of them only as a stranger I'd rather not talk to; I feel apathy now instead of hate like I used to.
I'm so sorry you're experiencing this. I hope I could give you at least a tiny glimpse of what it can look like on the other side. You're not alone.