Heartbroken--support please!

I apologize for the length in advance, but I'm about at my wits end right now.
My boyfriend of almost a year and I broke up last night over the phone. It is a long complicated story, but the gist of it is that we haven't been extremely happy recently--he has not been working very hard for this relationship land lacks the consistency that I need. (As a side note--He has always been a very physical person, but we haven't made love in weeks and our overall intimacy level had plummeted. Although this is definitely not something that I would expect of him, it points to the issue that something was very off.) I felt like I was constantly trying more than him to make this relationship work. Even though I know he loves me more than anyone else, he's my best friend, and I would trust him with my life, I was being thrown on an emotional roller coaster constantly. The highs were amazing, while the lows were heartbreaking. Last night, I had a long chat with one of my closest childhood friends, and after she heard my entire story, she suggested that I should break up with him. It made so much sense when we were talking, so I decided to give him a call that night (we are in different cities for the next couple of weeks, and I wanted to get it over with ASAP).
We talked, and he seemed pretty unphased. It was probably shock. Even as I called him, I felt like I was making a mistake. I felt like it was wrong to end it on such short notice. 
I talked to him today and went through a long spiel about why I did what I did, but I told him that if he was willing to work towards changing things, I would really like to continue working together as a couple. However, long story short, he downright refused, saying that we agreed before that if we ever broke up again, we wouldn't get back together (He broke up with me about half a year ago because he was going through some depression and was pulling away from me. He realized that he made a mistake, and tried for a month to get me back. Eventually I did forgive him and give him another chance.) I feel like I made a mistake breaking up with him yesterday, but he will not forgive me or try to work towards fixing the relationship. We both love each other so much still, and we both say that we wish we could keep working as a couple. However, while it seems completely against his nature, he refuses. 
I've never been a girl to let myself get super beat up by a relationship, but right now I feel like I'm completely falling apart. I feel physically sick, and the only emotions that I feel are extreme regret and sorrow. I can't stop crying or feeling my heart break over and over. Please-- I don't know what to do.