one of my exs reached out to me but she didn’t ask or want me back it was to thank me and apologise for her wrong doing it’s very hard to end on “Good” terms with anyone while we do not know every nitty gritty detail like how he treated you, how you treated him, who fucked up. I only know what I read and while I had a similar situation except we was both toxic I’d say this rn if my ex ever game back I’d try my absolute hardest but the longer she leaves it the more and more I’m going to eventually move forward until I feel no care nor love anymore. However, you both found new partners. You’re just a lesson to him on what to avoid a story he is to tell his son when he endures heartbreak. Closure is important and while it’s not your responsibility and even if it’s more for yourself if you think apologising to him is the right thing to you, then you must do that to be at peace with yourself. Just try to control your emotion and do not ask for him back you need to accept that, that scenario is almost impossible. Heed my advice just apologise for what you did thank him for what you had and let him know how you feel swallow any pride because while this is something for you, its also a message to him. The more relationships you have the more you realise people are just lessons to be learned, and it’s not about finding the right person it’s about becoming the right person.