Leaving my kids

My husband and I are in a mostly toxic marriage, we have been together about 10 year. We have both been in active addiction together mine weed and his m3th. We both have struggled to stay sober. The drugs seemed to go hand and hand and whenever he was about to relapse he would buy weed for me so it was harder to cach on to. We are both sober now, but rarely last over a year, my mental health is deteriorating, I sometimes feel suicidal. I am now at the point where I feel like I cant stay in the same home anymore because I want to stay clean to have a better career and be a present mom, have intelligent conversation and grow. I just dont ever see him getting clean for good and I dont want to be on a roller coaster anymore. I also have an 18 year old who still smokes weed, and while I dont want him to, I dont want to make the separation and me leaving in any way about him. This is our fault. But my main problem is I have two younger kids, I cant afford a normal place only a small room for rent, my plan is to move out and save for a bigger place so they could be with me. But I feel absolutely horrible leaving my babies, am I making the right choice?