I'm sorry for your hurt, Avery HG, and it may stink to hear, but it's my thought that turning to another guy won't solve things. It would be like a band aid, I think and what if things didn't work out then?
My interpretation of your post is that you may be in some need of release and it sounds like you have a lot of frustration and pent up feelings and thoughts.
For a brief time I felt as you did with DD and that I had to protect her father but also her from what he had done. Now I answer her questions as matter of factly, but simply, as I can, but I tell the truth to her and think it's important to a kid to have the truth-even the little ones. We all deserve it.
You sound like a good mom and I can hear the Mama Bear coming out that I've had to work on, too. Mama Bear's not easy because in some ways we have to put those instincts aside to protect ourselves and our kids, even though it doesn't make sense.
We can't control our WSs, can we? We can't force them to want to be family people and we can even cause them to run further.
I'm sorry for your pain and for your son's pain, we have that too and every time it happens again, I see and feel our daughter's pain freshly. I've learned a lot with occasions, but now what I like to do is talk to her a few days before an occasion.
I tell her simple things and I want her to feel or think that it's okay to honor a person even when it's not the very day. It's still important and reaching out and showing appreciation on a different day. We've gone through similar things and I finally put a stop to it by not contacting him on those days other than "Happy birthday" or Happy whatever day. I let her know that I did, and now I have her call and leave a message, so that she can have done something and I can step aside.
I had a lot to learn about stepping aside and he is falling from grace in her eyes with each disappointment. I'm done cleaning up his messes, but I help with her emotions by saying, "I'm sorry" and a hug and nothing about him. Then we get up and go do something distracting.
Sorry for my long post.
A person is a person, no matter how small. -Dr. Suess
Perserverance and spirit have done wonders in all ages.