I usually never hook up with my brother in laws (BIL) friends. Never told not to but just a respect thing. I broke the rule 12 months ago & we hook up on/off again still. Everyone’s adjusted & nothing was ever said. When I’ve seen the friend(call him L) the last couple of times he’s tried to include our other friends (also his roommates). I’ve always objected because of my BIL etc. On Saturday night I didn’t say no. I gave in & hooked up with all 3 roommates together. Had the most ridiculous mind blowing amazing fun. Was kicking myself for not doing it earlier. We all agreed that we would not tell anyone & it would be a secret. The boys also said though BIL wouldn’t care blah blah blah. I definitely know him better. The next morning when I got back to theirs he quizzed me on who was there & what happened. I shrugged it all off. I know the boys won’t tell so I should be safe. But sister who’s married to BIL is also my best friend. Like tell her everything. The world doesn’t sit right unless we’ve spoken every day. It’s killing me not to tell her. I know she will be somewhat okay with what happened & try not to judge but then by telling her I have to ask her to lie to her husband. WTF do I do? I’m dying to tell her. Is that just selfish? Should I get over myself?