Im in an uncomfortable situation with my boyfriend and I dont know what to do!?

So im 15 and I have accepted myself as a lesbian for about 2 months now, the problem is, I have a boyfriend. I wanted to experiment having a boyfriend when I thought I was bisexual, but I realized I only like him as a friend. I want a girl! And he puts me in awkward situations, like I really don't want to kiss him, but he tries to get me alone to kiss him. And he always puts his arm around me or holds my hand, and it feels so awkward and gross to me. Defiantly not how it is supposed to feel. How do I brake up with him?!? He is super nice and likes me a lot but I just don't feel the same! Help!