This is a bit of a stickier situation than it would normally be because you have a child with her. Normally, the easy answer would be No Contact like some of have said. However, I assume you want to be a part of your son's life, so here is what I believe you should do:
1. Most importantly - STOP spending your visitation with your son at her house. This is a terrible idea and gives her complete control over the situation. Take your son to your mom's (for now) - but hopefully you have your own place soon so you have 1 on 1 with him.
2. Do a semi-NC; ONLY discuss your son and things that affect your son. Do not discuss the two of you, and stop letting her make you look like a fool by playing with your d1ck and telling you "maybe" you can get back together. That is unbelievably degrading.
3. Get serious about making yourself better - THEN seeing other women. This is a mindset that you need to adopt and it may not be easy with you having such a severe case of oneitis for your ex. Most guys go to the gym as this helps put focus back in their lives. You also need to move out of your mom's house (and maybe improve your job/prospects - I didn't see anything about this but only read the OP). If you do these two things, I can almost guarantee you finally lift this dark cloud that is your ex out of your life.
When she sees you turning it around, don't be shocked to see her put on the full court press to keep you grounded in her reality. She will want you to stay like you are for her own validation. Don't fall for it. Good luck.