Should I leave?

[Sharon93]

I've been with my youngest son's Father for almost 2 years. He's always struggled with alcohol and drug addiction. We don't live together, and I'm now aware that he's been using illegal drugs, as well as alcohol, while his young daughter is in his care. He will also drive under the influence with her in the vehicle. I'm not comfortable leaving the baby with him unsupervised and I've begged him several times to stop, which he hasn't. But our son is only a couple of months old and I don't want him to miss out on having his Dad around. Should I stay with him, remain living apart and keep a close eye on his behaviour while allowing him to see our son with me, or leave him, and hope that one day he can see what the drugs and alcohol are doing to his life/relationships and eventually gets the help he needs?

Just leave. And safeguard your child from him. That should be the priority.

Don’t live in hope that one day he’ll come to his senses. I think you need to read your post back to yourself.
Why are you considering putting your baby around substance abuse. Look at it in a different vision, get him to sort himself out ! Your son will still be there - he can make things right when he’s in the right head space. Take control, set boundaries - then see if he changes, not hoping he does.