My husband and I have been married for a year, together for 3. Years before we met, his godsister (mom's best friend's daughter) moved in with my MIL after her mother died. My husband was still living there at the time. They started having sex, and my husband swears it was only out of boredom and convenience. She came out the closet a couple of years later and has a long-term girlfriend now.
Apparently she's in town temporarily for work but her job isn't providing accommodations. My husband would like for her to stay with us since we have a super nice guest space. Claims that they grew up together and it's the least he can do for "someone who's like family". I reminded him that people don't usually screw their family members. But he swears they were just young, stupid and bored and it meant nothing and there was no attraction between them. However, he let it slip once that he spent over $1k on plan B bills while they were sleeping together so clearly there was a tiny bit of attraction. I straight up told him no, she can't stay with us. I'm just not comfortable with having a woman who's felt my husband's d*ck sleeping under the same roof. He says I'm being unfair because she's a lesbian now so there's no threat and the sex was long ago. But I just can't get over that they were intimate at some point, no matter how long ago and who she's attracted to now.
Am I overreacting?