I, alongside many, many women I assume have struggled with such intense issues. It is one of the hardest things to control, emotionally even moreso than physically I would say. You should be sure that God loves you, that you are a pure daughter in Christ and that he has a brilliant, special plan for you. Do not go back on your vow, God will reward you for it and has many great things planned for you if you submit to him. A really hard question I guess you have to ask yourself is, does God want me to still be in this relationship? Is it his will? I suggest you spend time in his word and his presence contenplating it. The Bible tells us that the devil installs fear in us to prevent us from recieving all God has to offer. So if you are fearful of your boyfreind breaking up with you out of the fear of being alone, this is the devil talking.

I'm sorry if that all sounds a bit weird, keep walking in Christ's light because he has so many good things to give you.

I wanted to say that I've read a brilliant book on sex by a christian author Paula Rinehart - 'Sex and the Soul of a Woman', who compassionately explores womens struggles with intimacy in great depth, giving great practical advice of how the holy spirit can lift us out of the crippling emotional bondage created by sexual intimacy outside of marriage.