first of all, i give you much credit for realizing that you need some help and for reaching out for it
!!!! that's more than a lot of people do. you're much stronger than even you think you are! don't forget that
!!! it's always unbelievably hard to break up with someone/to lose someone or something dear to you, but all i can say from my own experience is that the pain,anguish, and later on, hatred, WILL PASS, given time.
when you go to see this person, don't be afraid. i was always very, very shy myself (like other things in life, you'll outgrow a lot of it--once again, with time), but as for now, don't let it keep you down! pretending and making believe helped nobody.
if you need to cry in front of this person, do it! if you need to yell, do that too! if you need to curse, and vent, and cry some more, let it out. let those feelings out--it'll make you feel much better. gather that strength from inside you and say to yourself you want to be feeling better, you don't want things to be the same anymore. you've had enough! talk, talk about the sadness, the not eating, the crying, the need to cut, and everything you can think of... only by opening ourselves up and letting the pain come out, do we get some freedom and some peace for our souls
like kj_johnson said, i don't know who're going to talk to, but if it's a genuine doctor , or therapist, or priest, or rabbi, DO IT!!!