How involved would you get in this

My step son is 20. Will be 21 in July. I haven't been in his life for an extremely long time. Only about 4 years. He's openly bisexual. Well I found out for the past 6 months he's been participating in an affair. I have multiple issues with this besides the affair in general. First one is there is a 7 year age gap. I get it. They're both consenting adults. It's just a tad bit weird. Second problem the person he's participating in this affair with is not only married.... He's a pastor... At the church that I work with. I'm not a religious person but I work. Bon profit that helps give stuff to foster kids and work with them. Especially during Christmas. So I know this pastor. We've had many conversations. He however didn't know my step son was my step son because we dont really talk about our personal lives. How they met was at the library. My husband has already had a talk with my step son about how this isn't right and it will probably bite him in the ass because he guarantees if this comes out the pastor is going to completely blame him and temptation and stuff. So me and this guy I'll just call him E did talk after he found out he was my step son. He tried to tell me that he knows this is wrong and all this and all I said was it's not my business but I whatever confusion he's having I wish he didn't drag my step son into it. Granted my step son is an adult so he made this decision to. He told me he knows this is wrong. That he's been unhappy for a long time. It's why he never gave his wife a child because he was always depressed and didn't want to bring a child into it. I asked if he loves my step son and he said he thinks he does but he is confused. Everything is confusing. I mean he's a pastor so obviously his beliefs are conflicting with his feelings. I said I will not get involved with whatever this is but if he is even half a man he will tell his wife.

I have some people telling me I should be a girl's girl and tell the wife and would I want to know if I was being cheated on. I would but I wouldn't expect the person they work with sometimes to tell me. Especially if I've never even met that person. I told him what I think he should do and I really don't want anything to do with it.

@Kim yeah I am probably just going to mind my business. My step son thinks he's in love but I can't see a scenerio where this all doesn't blow up 😐

Edit: I never said I haven't been in his life IN an extremely long time . I haven't been in his life FOR an extremely long time. I've only been with his dad about 4 years. I didn't like take a hiatus from my marriage or anything. I've been in his life since he was 16.

Edit 2: Idk why it's weird My husband didn't tell the wife. He has no obligation to the wife. He only has obligation to My step son. My husband would never say anything to the wife. He doesn't even know this pastor. He just knows his son is doing something stupid because he's young and dumb. Also, take it with a grain of salt because E could totally be a liar but when me and him talked he said he hasn't had sex with his wife since they started whatever this is. Idk how true that is. I just know I don't want to be apart of whatever this is anymore. Like Kim said all I can do is offer emotional support when this blows up because I don't imagine a world where this doesn't blow up in his face