Me and my STBXW are currently going through a divorce. We have 2 toddlers. My wife took our daughters and is now staying at her sister's.

I found out that she's been calling and texting this number a lot, like multiple times a day, and the calls sometimes last over an hour.

I was able to verify this person's identity, it's someone she knew back from high school. He lives close to her sister's house.

I believe my wife is cheating on me with this guy, now I don't really care what she does, but I just want to use that in court, because she's the one who left me.

How do I need to proceed? Should I talk to him?

Any advice would be greatly appreciated.