The relationship I was in when I was using the most, now that I've been out of it for quite some time, was one of the more toxic and horrible things I did to myself. She wouldn't leave, I wouldn't let her... It boiled down to a pathetic codependent relationship that I wish one of us had, had the balls to just end it.
If you live together. Find a way to move out, today. If you don't live together you still need to end the relationship as soon as you can. If you're serious about staying sober you split and you do it fast and clean. Then lose his number and the number of your connections and your friends who use. Get new friends, because the ones that are using won't help you stay sober. They will help you relapse.
I have a coworker who just lost 14 months of sobriety because she got back together with the ex boyfriend who still "occasionally" shoots dope.
I'm curious to know how old you are and how much time do you have? Also, what was your drug of choice? Do you have family you can stay with? Do you have a car? Can you leave where you live to a place where you have sober support? If you do, drop him and go somewhere that is safe.
Right now you just got clean and you love this guy. He stayed with you through recovery, which is huge, but unless he's willing to also get clean your long term outlook isn't good sticking around him. It really is that simple. He might beg you to stay. Being an addict alone sucks. He might cry or threaten when you end it, so have a sober friend on standby. Someone who can get you out, help you gather your things.
If you'd like this is what you can say to him:
"I love you, but our lives have come to a point where we can't be together any longer because I'm trying to change myself for the better. I really hope you can do the same someday. I can't live here. Right now and forever, my sobriety is the most important thing in my life. If I stay with you I don't know what will happen to everything I've worked so hard for these past #insert sober time#. I'm leaving because I think this is the best thing for me. Please don't contact me, I need a clean break. Goodbye."
Hopefully you'll have packed and you can leave. I'll say it once more, if you're serious about staying sober, you will end the relationship and move out and never look back. Remember the girl I was talking about? Once we finally split we spoke once in person and twice on the phone and that was a month, a year and two years after the fact respectively.
Update us. Keep in touch with the board. If you need to call someone and talk you can PM me your number or ask me for mine. I'm willing to support you through this. I know I'm a person on the web, but I'm still willing to be there on the phone with you.
Good luck. Stay Strong. Get Out.