My ex and I split in January 2020 and he moved out 8 weeks ago.

He didn’t think I was serious and figured we would get back together, he only took me seriously when I told him that if this house wasn’t owned by my brother then I would have found a place and moved out with our son already and he wouldn’t have know I was gone till he finished work.

How do I get him to stop messaging my sisters?

I have told him already but it’s it sinking in that he should only message or ring my siblings if there is a emergency to do with our son and he can’t get hold of me.

One sister he kept comparing me with her and use to say things like “that dress she had on was nice it would look good on you” this sister has a more out there personality then me, but he doesn’t know I found out he was googling advice on how to sleep with his SIL or wanting to play strip poker with his SIL.

Another sister he keeps messaging asking if she found a new rental to move to and if she hasn’t he says she can move in with him. Iv told him he needs to stop asking her about it because it has nothing to do with him. This is also the sister he told his mum was his “dead beet SIL”. She has told him she can’t afford to pay half of his rent plus utilities. Our parents have told her that moving in with him is a big NO and she will not be moving in with him. Our parents also think he will try and have sex with her if she did move in with him because no one else will and they don’t want her to become pregnant to him (neither do I). My parents and I think he will also use her as a babysitter the nights he has our son so he can go and play his computer games and not have to parent. (If this sister can’t find a new rental she will be moving in with me to our brothers rental property)

My other sister has just got back to the country after being stuck in the UK, she has done her 2 week quarantine and is now living with the sister in the first paragraph. I don’t know if he is still talking to her but he was while she was in the UK asking how it was all going and this was after we had split.