My mother in law had been bothering me for ages about looking after our baby for the night, but I was reluctant because when her new boyfriend is around she seems to do really stupid things. She has 2 other grandchildren (3 and 4) and has left them unattended in a 1st floor maisonette while she and the bf went out to have a smoke (I think his was weed). Also she has nothing at her house to look after the baby and lives 30 mins away so I'd literally have to pack EVERYTHING into my car and take it all to hers, which I just see as too much hassle (she doesn't drive).
So.... At Christmas I compromised. My partners Nan was away staying with family for a week so I said his mum could look after the baby at his nans for the night (his Nan often babysits because she's 5 mins away and has loads of stuff there already).
Everything went fine, she had the other grandchildren there for the night as well.....until today, when I find out that her by actually stayed round that night and it turns out that someone else who lives in the house heard her and the bf 'at it' that night......when my child was sleeping in the same room. She was 4 months at the time and I know she has no idea what's going on but considering I'd already expressed that I didn't want him staying over when she looks after the baby, I feel like this is a massive breech of trust. AIBU when I say I don't want her looking after the baby again overnight?