After half a year, why isn't it getting better

Hi reddit, normally I don't use reddit for advice but I'm really stuck right now. So a while ago I was in a relationship with a girl (let's call her daisy) for about 3 years, eventually we couldn't work because of my jealousy and her openness towards everyone. I kept telling Daisy) I would change but ended up not being able to because of her (in my eyes) cluelessness when guys were flirting or not. We also had a rough start since my best friend (let's call him Maro) had something going on with her before and also took a relationship with my other ex a month after the break-up. Absolutely wild, i know. Here comes the even better part. When Daisy and I were going through a break-up, I was in the deepest low I've ever been. Even worse, a month later I found out she had slept with Maro when I came over to his house because I knew they were both at the same party (stalking much). Keep in mind, the day I came over we were a week into the break-up.

So that's my story. Now I'm finally feeling better, I stopped using drugs after a couple years and soon going to have a new job. However, I keep having dreams about them or me getting back with them. Like a ghost that keeps haunting me even if I'm trying to let go. I know it's normal, but how is it still so strong that even after half a year I can't seem to let go. Advice?