Toxic girlfriend and Lying boyfriend: Struggling with keeping healthy patterns.

My partner and I just separated after almost two years (I initiated it) because I caught him lying to me about where he was. As it is, I was already very unhealthy as I was extremely controlling and possessive but I wasn't until him and I suffered a trauma together which was my assault. After that, we have been spiraling since and it's been extremely difficult for me to cope after the break up. He added his ex girlfriend back on social media and that completely destroyed me. I know everyone says he is single now and I shouldn't care but all I want to do is seek male validation of my own. I'm aware it isn't healthy but I'm so angry because we talked about a possible further future together and he did this. I'm such an emotional mess. I don't know how to cope...