Would you keep talking to your ex? Plz read.

I broke up with my ex a few months ago.. the entire relationship was super toxic.. we would drink too much together etc. I'm 25 and dated him for about 10 months. I had to block him for a bit after I broke up with him. He even kept coming to the club I work at.. he's been trying to talk to me via Twitter but I've been very slow to get back to him. I can see a preview of what he's saying but I don't open it so he doesn't know I've seen it.

I'm conflicted whether I should talk to him or not. On one hand, I know he deals with mental illness (bipolar, possibly borderline personality disorder, lots of suicidal thoughts) and I probably wouldn't like feeling ignored but on the other hand I feel I shouldn't spend a second talking to him because he has such a strong negativity about him. He is quick to try to make me feel bad about living my own life. I feel he is not my problem anymore. I feel I can't even trust him at all. If I tell him one thing, he will tell everyone else. It makes me feel sad to talk to him and know he still misses me. I don't want to be too harsh but I need to do what's best for me. What would you ladies do? Have some sympathy or ignore him and keep moving forward?