What Would You Do?

I was with a guy for 3 years, we were engaged but it was actually a horrible relationship. He cheated on me because I "didn't keep the house spotless" which is hard to do with 3 kids, and he is a narcissist.

Well to make a long story short... he cheated on me once last year and I left and decided I was done for good. 10 days after I left, I found out I was pregnant. I did sleep with my best guy friend once with protection, I didn't plan to it just kind of happened. March of this year I had my baby. And he looks exactly like my best guy friend. I told him about it shortly after he was born and they both instantly fell in love with each other. If you imagine a perfect father, it would be him with my son. They adore each other.

We recently did a DNA test on the two, I felt confident he was my friend's baby, because they look identical.

We got the results back last week and he is not my friends. He is my ex's.

My ex and I have another son together who just turned 2, so I talk to him on a daily basis because we do week on week off with him. I haven't told him about it and don't even know if I should.

When we got the results back, my best friend was devastated and I've never seen someone cry so much. I cried too.

I want to do the right thing, I want to do what's best but I don't even know. My ex parties a lot and most of the time our two year old is left with his parents when it is his week. He has two potential daughters with other girls (that happened during our relationship, his cheating) and he personally told me he didn't care to know one way or the other if they were his or not. I just feel bad for not saying anything, but then I don't because he's already so close to my friend, and jabbers "da-da" at him. I've prayed and looked for signs and I haven't gotten anywhere. Please don't judge or be rude, I'm just asking what other ladies would do in this situation.