What do I do?

My sons father and I was in a on and off again relationship. He left to the military and I thought he would go to become a better individual. He called me to say he missed me and my son. He sounded like he was really becoming someone better. Well within the same week of him calling me I found out that he has a whole new baby on the way. His sister text me to invite my child to the baby shower. I was extremely angry and hurt. I cut off communication from him and his family because I felt like everyone knew but chose keep me in the dark. I'm so disappointed in myself because I had so much for him and put all my trust in him when he gave me false hope and lead me on like a fool. I don't ever want to speak to him and feel as if that's best for me. As far as our child if he wants to see him then he can go through a third party and see him at a place neutral such as my grandma house where I won't be around and won't have to see him. I'm so angry and feel like such a sucker for believing a liar and falling for lies. I need help in figuring out what to do.