I dont know if this is the right place to post. If it isnt I'm sorry.

My ex (the father of my son) was very involved in his life even though we had broken up. We had a great coparenting relationship. We would still hang out and take our son to do activities together. It was great. Then he met a girl (who is now his wife). When she first came into the picture she was really friendly and we didnt have any issues. But then things started changing. I could no longer communicate directly with his father I had to go through her. He changed his phone number and I could only call hers. Our calls were always on speaker so she could hear. Then whenever I would try to have a conversation face to face with him she always had to be involved. That started causing problems between her and I. I felt like she was extremely insecure and controlling. She was a girlfriend coming into a situation that was already developed and was trying to change the dynamics of the relationship we had for the sake of our son. Anyways about a year later she ended up pregnant. 2 months after they had their child his communication and visits completely stopped. She changed her number and I could no longer get a hold of them. I tried so hard to get a hold of him. I went to his mother where she let me know that his girlfriend made him chose between my son and their child. He chose them. He completely abandoned my son. He was 5 at the time. After a year of me trying to get his father to be in the picture I decided to let it go. I wasnt getting anywhere. He didnt want our son anymore. Today I ran into him...our son was with me. It's been 7 years. My son remembered him. He ran into his father's arms and cried. It broke my heart. I froze I didnt know what to do. We spoke for a few minutes. He asked for my number and I gave it to him. Thinking about my son and wanting him to have another opportunity with his father. My mind is racing right now. What if he messages me? Do I let him see our son? I feel like I'm caught between a rock and a hard place. If I dont let him I feel like my son will blame me. But if I let him and he comes back and disappears again I'll never forgive myself. I dont know what to do.