Me and my Brother in law slept by mistake after gone drunk

I’m 29, my husband’s 31. His parents held a family party for his niece’s 18th
birthday last weekend.

Everyone was there, including my husband’s brother who was home from working
away in Saudi. He’s 36.

We all get on well and there was plenty of alcohol and food. It was a
brilliant party and we carried on drinking and dancing into the small hours.

My husband went up to bed before me and said he’d be waiting for me. I
followed him up 20 minutes later. I got into bed feeling frisky and we ended
up having good time.

I woke up a couple of hours later and sat up to get a drink of water. I pulled
back the curtain to let some light in through the window from the street
lamp right outside the bedroom.

I looked round and got the shock of my life when I realized I was in bed with
the wrong man. The man beside me was my husband’s brother. I’d gone
into the wrong bedroom and I guess my brother-in-law thought it was his
lucky day. We had all had a lot to drink.

I ran to the right bedroom and crawled into bed with my husband who was fast
asleep. Then I realized I’d left my underwear in the other room, so I
sneaked back.

My brother-in-law was stirring so I hissed that we must keep quiet about what
had happened. He just said, “Whatever.”

He’s flown back to Saudi now but I don’t know whether to admit everything to
my husband. If this comes out I’ll lose a man I love more than anything and
cause family ructions.
ADVICE PLEASE