Please help me with my Jekyll and Hyde ds1 (11) !

[HamsterPoo]

He can be such a sweetie but atm is spending a lot of time being really horrid to ds2 (8) and dd2 (5), lashing out at them, scaring them, saying really cruel things
Don't know how to deal with it

have you talked to him about it?
asked him why he does it?
asked him how he would feel if someone bigger kept picking on him?

i know it's not quite the same, but my almost 6 yr old is the same with his 2 smaller brothers. I've told him it's just like bullying, and won't be tolerated.
he gets a warning the first time, and if he does it again he has to go and find something else to do in another room

basically, if he can't be trusted not to be unkind to them then he needs to be in a different place.
am not sure how you can implement that with an older child, but might be worth a try?

Thanks. I have talked to him about it. When he is in a good mood he agrees with me and makes promises. When he is in a bad mood he says, "Whatever", makes rude hand gestures and calls me a bitch.

Has he just started senior school by any chance ???? My ds1 turned into a little sh** aged around 11 ... cocky, rude, physical and generally obnoxious. A mixture I think or change to really big school and hormones. Good luck

Yes he has

However, exp told me this eve that he blames me for his behaviour. So, it's all my fault. That's okay then

no wonder he's yr ex! what a shxx

Yes. Unfortunately he is still living with us.