SO question

Ladies please give me your best advice, I'm stuck.

So last week I looked at my SO phone and saw he was asking my brother for cocaine for a friend my brother said he didn't have any so I confronted my SO and told him I'm not ok with him trying to get drugs for friends because he's a dad now and doesn't need to get into that stuff and he said sorry he totally agrees and wouldn't do it again.

Fast forward to this week I look at his phone again and I see he picked up meth for the same friend on an Indian reservation... what the fuck one week after he said he wouldn't do it again

We have a 9 month old together and he's doing it for "extra money" $20 is all he says.

What would you ladies do? I feel like I should leave but I don't want to put my daughter through court and be separated and have to move, I can't afford to live anywhere on my own. Ugh