eek... he is bipolar, so maybe the chemicals in his brain will eventually level out and hopefully he'll get over you. im not sure my case is the exact same, but that seems to be how i got out of my "crush:"
i was in a position recently obsessed over a girl id never even had a relationship with (though such good friends i always had a lil crush on her)... for bout a week i went at her daily, tryin to talk her into kissing me and feeling our relationship was over ...each time. this is NOT normal for me, but i was suffering inside, and didnt know why. i was so _delusional_ i thought our friends were conspiring to hook us up one day.
i came to my senses only after the girl left on a trip and i believed she was going to stay w/me instead - she didnt, tho i still thought it was my fault somehow - i only broke after my roomate came in to yell at me for making a fool of myself around our friends n i tried to explain everyone was against me. slowly i regained control as i pieced together all the other parts of my life that had changed round the same time...
i hope this sheds some light from his perspective, it was devastating to my ego/stability after i 'woke up.' u can imagine how he will feel when he comes to realize his mistakes. in my case, the more i blew my chances, the more i wanted to prove myself to her and eventually i was so delusional i had to admit my fault. imho he may only come to terms if he sees you're actually dating someone else - otherwise, medication n therapy are his best solutions.