We all make choices and we all have to live with the consequences. Just sad when some poor choices affect innocent children. Do better. Being a parent is supposed to place your child above all else. If you don't then maybe you shouldn't have children.
Friendships change over time. It doesn't mean you have done anything wrong. It doesn't mean your friend has done anything wrong. Stop trying to figure out what you did wrong or blame the other person. Remember the friendship you once had as around memory.