Welcome yensid!
You are already a winner in my book! 4 mo married and you kicked him out? My H is upset I did it 18 years in!
The finances sound a bit frightful. How are you in debt for his addiction?
I'm thinking you are exactly right in your post in that if you make decisions based on your kids' safety and well-being, you are on the right path. So protecting your custody is crucial.
You have every right to end things if you decide to. You can decide you don't need the drama of addiction in this marriage. You can change your mind hourly. I do that sometimes...
There is a lot of wisdom here and in the sticky threads at the top.