What should I do

[GardenGnomes]

Sorry if this isn't the right section but I really need some advice.
I had a baby last June and me and my little boys dad split up at the end of last year. We get on okay now but didn't when we first split.
I've been staying with my mum and sister since me and me ex split. It's been okay, if a little cramped (2 bedroom house with 3 adults, baby, 2 dogs and a cat!) until recently.
My sister has severe mental health issues. Until recently she's controlled it a bit but in the past week she's had two meltdowns. This morning she's got very upset (screaming, crying, banging, throwing things - not in the same room as me and baby) because I fed my son chicken (she a vegan).
I'm so worried about my little boy. I know she won't hurt him but he can hear all that's going on.

I don't have anywhere else to go. I have no friends and no family that have space for us.
Me and my ex had just bought a house together. We have joint ownership. He doesn't know about how bad it's been here because I'm scared he'd try and get custody of our son.
Do I have any rights when it comes to the house? My ex wants to sell it but could I just move in and refuse to leave? Please help ☹️

No, you can't just move in and prevent the house being sold. Although he may need to obtain a court order to sell it, if you - as joint owner - don't want to sell. But fundamentally, neither of you can just take the other's share of the house by living in it and refusing to sell.

While you still jointly own the house, however, you are entitled to live there. So you absolutely could move back in until it sells.

It certainly sounds like you need to get your son out of the atmosphere he's currently living in - it's no way for a child to live. So I think you should consider talking to your ex about moving back in with him until the house sells.

If you don't want to do that, you might wish to consider whether the best interests of your son could be met by having him live with his dad until you can get back on your feet, and provide him with a safe place to live (perhaps once the house you jointly own has sold, and you have your share of the equity).