Wtf is wrong

I saw other post about how their spouses cheat and stuff so I figured I could state somethings. My partner had a affair and the person (affair) now moved 9 hours away but they are still texting either, my partner wants to be friends with this person, how can you fix your relationship and be friends with the person that you slept with behide my back and are still texting.

Anyone else deal with this type of crap before,