Caught up in an affair?

I’m 25, he’s 39, almost 40 in October.

Married (but claims to be separated) has 8 kids (5 are hers that he took under his wing, 3 are from him, one passed away at the age of 4- so he has 2 biological kids).

He’s in the marines, almost at the retirement part so he’s a MSGT (something like that-E8-E9 ranking?)

We had sex on the day before ovulation, day of ovulation and day after.

The first session was more like a rape situation.

My question is, what do I do? He came over yesterday night to pick up something he left, and he pushed his way through the door again.. Do I tell the wife? Do I just block and move on and handle this situation on my own?