I don't trust him!

I’m a 21 year old, I’m sooo confused ryt now, there’s a guy that I’ve been friends with for 6years, but we have been dating for 2 years. While we were dating he was also dating hi gf as I had my bf at that time, we were actually both cheating on our partners, then our thing ended up being a solid relationship because we were not hiding it from our families and friends, and we ended up being together for “good”. We would help each other with a lot of things n we would support each other in everything we do. His chick knw nothing about us, but she dumped him cz she had a new boyfriend. Now things changed when this chick came back and demanded him. He even told the guy to dump me because she’s back and she wants her “BF” back. I fought for him but clearly I wasn’t doing enough. He ended up breaking up with me because he ddn’t want to hurt her cause he was blaming himself thinking he’s the reason y this chick break up with him, then that was it for ur, I didn’t wana cause drama I accepted that we over and I tried to move on but I couldn’t because I love him n I know he does too, but I was left with unanswered question, y he choose her over me. We didn’t contact each other for quiete some time I missed him a lot. This whole thing happens last year, while I was still going through that, I met a guy n I dated him n we would have sex, but while having sex with him, I would cry because of my ex, it was so hard for me to accept, n yes I admit I moved on very fast after the breakup, and i would tell him the truth when he asks why am crying, n i didn’t hide the fact that i still love my ex but he would understand, but i got confused when my ex came back and he was like i want U back in my life I’ve made a mistake n people learn from their mistakes, i fell for that we gt back after nit being in contact fir 5months, we are back together taking things 1 step at a time,i dumped the new guy i met because i didn’t really love him at that time i was angry,sad and lonely. No am not sure whether i made a wise decision or not cz i don’t fully trust him although we are I love.
Please help xoxoxo