Being friends with an ex

I dated my ex for 3 years and he was pretty shitty to me. I know he loves me but he didn’t treat me right. He cheated on me with his ex in the beginning. So there were trust issues right away. I took him back and wanted to work it out. Then it was just lies about stupid shit. Then we break up and get back together like 3 times in the past year. He got involved with coke and always chose friends over me and partying. So now it’s been two months since I completely ended it (on Christmas) My friends tell me to never talk to him again but I’ve been miserable with trying to do that, like depressed miserable. So I finally answered him and we’re going to try the whole friend thing while he tries to get his shit together. Does anyone think this can actually work? I don’t want to tell my friends and I need some advice I guess.