Broke up with a decent guy for my son's father, who left me for another girl 7 months ago... help :'(?

I'll try to keep this short. My ex left my son and I for a girl 9 years my junior, I am 26. That was seven months ago, and 4 months ago I began seeing another man who has serious commitment issues and problems showing affection of any kind. I do know he liked me only because of his body language and the things he did for me, though he was not sure if he wanted a relationship. We broke up 3 weeks ago but continued seeing eachother. Enter the ex about 2 weeks ago. I still have feelings for him, and we decided to get back together. Now that we are, I'm not sure how I'm feeling. It's mostly guilt for blowing the other guy off. I feel horrible and also naive due to the fact that my sons father is a world class manipulator. I think I made a huge mistake and now I don't think I want either of them. Uhhh... help!