How do I cope with this?

My boyfriend's best friend is constantly causing trouble for us. He is gay and not with anyone himself and he keeps saying my boyfriend is using me for money. I am not rich .. just I work full time and he works part-time and I sometimes buy extra drinks when we are out. My boyfriend is caring and kind and always tells me he loves me. I find it hard to believe he doesn't and it is all an act, for the sake of a few extra drinks. Not like I am buying him expensive gifts or anything. It hurts though... there is an implication that he can't like me for myself, that it has to be for money. Him and his "friend" have currently fallen out and I don't really want them to make up. I feel like his friend won't be happy till he has destroyed our relationship. How do I cope with this?