4 years down the drain is better than 6, 7, 8,9, 10 years down the drain.
Addicts dont let people go when that person has so much use for them. When you absolutely have nothing to give them and refuse to, they move onto another victim. That is not love. You spend so much energy caring for this person in exchange for what? Chaos. That is no way to live.
It's your decision, to stay or leave this person but the wise thing to do is to cut him loose and take control of your life. It hurts a ton in the beginning but time really does heal everything.