I do agree with Steelers on a lot of points she made...but you have attempted contact...and when you receive nothing, what else can you do. That's where I believe your situation is much tougher and a little different here.
My ex is very similar...but would have contact with us if I would allow it. I don't think it is appropriate now since he has married ow. My kids were from a previous marriage. He has been confused in the past about what he wants and it just caused more problems for us. Another story.
Their 'no contact' makes us feel as if we meant nothing. But I believe your ex has some issues he has to work through. My kid's real father is similar in a lot of ways. He attempts contact now, but is still a bully to me so I can't find any common 'middle ground' to work with. We have been divorced for 12 years now.
I think you are on the right path in understanding just how important YOU are. You are realizing that you quite possibly weren't treated well in the situations that you shared in your posts. It seems your ex had some unsavory friends...LOL. Is it possible that you 'married down' and he just was not worthy of someone like you...JMO. Forgive me if I'm way off base.