Coming in a little late on this, but hope this helps...
I did call the cops and had my addict taken to jail. It was the second saddest day of my life (the saddest having to have her committed 10 years later).
Jail saved her life at the time. She went back to drugs and the commitment saved it the second time.
In both cases is wasn't me who sent her there, it was just me who called the cops to pick her up when she came to my house - I knew she was violating probation and they came immediately. And it was me who petitioned the court for commitment (they took it the rest of the way). Neither of these actions would have been possible if my addict was not an addict, so I didn't look at it like I was doing it - I was just cooperating with consequences that could save her life. I didn't care if she hated me forever - her life was more important to me.
Also - When I did an early intervention, I realized that the only way I could truly set boundaries with my niece (who is like a daughter to me) is if I accepted the fact that she may do something to get herself killed (and believe me, she did many things) and I may have to be the one to bury her.
Why am I telling you this? Because until I was ready to call the cops or accept that I cannot protect her if she won't protect herself, my life was insane and she was getting no better. Before I accepted my helplessness, my life was unmanageable in the face of her addiction.
Romantic relationships with addicts, though, are maybe a little harder - because there are different dynamics. They say women fall in love with a man's potential - not his current state. Normally, this is a little disappointing, but when you fall for an addict, it can devastate your life. 1/3 of addicts get better after treatment, another 1/3 take many treatments before getting sober and about 1/3 never recover.
If you have fallen in love with your addict's potential, you may be betting on some pretty long odds.
One last thing - someone on this forum once gave me some wonderful advice - work your own program like you wish your addict worked theirs. That means, get out the 12 steps and put "codependent" in place of drug of choice. Are you ready to admit you are powerless in relation to your addict and that your life has become unmanageable? Are you ready for sanity?
Of course, focusing on an addict can keep us from focusing on the scary parts of our own lives. It can be complicated.
Wishing you the clarity you need to make your life manageable and become the kind of mother that your little one needs you to be for him/her.