u/Ok_Comb5055

I (22 trans male) have been out for a few years. When my grandmother died at the start of last year my second cousins son started reaching out sporadically.
This guy is in his 30’s, has a wife and two young kids. I don’t really know him well as he would be with the adults at family gatherings and I would be with the kids.
Over the last year he’s reached out, asked how I was and then stopped replying for a few months. Today he reached out again and asked to add me on snap chat. I agreed, then things turned weird.
He turned the chats to disappear instantly but I have a habit of saving messages as my ADHD means I forget what conversations are about.
He quickly asked if I could keep a secret. I instantly got a red flag but wasn’t sure. He said he was ‘curious about trans’ then revealed that he has a fantasy of sleeping with a trans person and vaguely asked if I would sleep with him.
I told him to speak to his wife about his fantasy as I felt very uncomfortable and he said that his wife wouldn’t get it.
When I mentioned the obvious ‘we’re related’ ( our parents are cousins), he said we weren’t because it was his step dad and not his real dad.
I tried to leave him on read but he kept messaging when I would do so. I know I could have stopped but I was confused and just responded. He asked if my boyfriend and I were in an open relationship and would sleep with him.
I called my parents as I was really confused and wasn’t sure what to do. They told me to just tell him no and ignore it/pretend it didn’t exist.
WIBTAH if I told his dad what happened?? Not to start drama but not to push it under the rug?