separation

So tonight I decided to leave my husband. He's had issues with pills for well over a year. I caught him 2-3 times saying he's not on them, when in fact he was. This past Christmas I caught him with heroin. He said he was done with it and had a nasty withdrawal on his birthday (dec 30). He started going to a celebrate recovery class at our church. I warned him and his mom (who supplied the pills) that if I ever catch him with anything I'm done.  Well today I saw a text between him and his mom about getting pills. So I decided that I have to leave. We have a 4 year old son and a 1 week old daughter. It's very sad because it's not what I want but I need him to know I'm serious and not subjecting our children to that. Also it's freaking Valentine's Day!!