I empathize with you. I had a similar situation, where the person desperately wanted me to go with them on everything even if I was low on sleep. I thought I was being a good friend, and I was even offended when people told me this friend was greedy and self-centered. But one day the person found a "better" friend, and told me off for not being good enough, even though I sacraficed whatever I was capable to even. I even broke up with my boyfriend for insulting them. If I were you, I'd gradually weed this person out of my life altogether, or keep it sparse. It sounds like the sort of relationship that would eventually wear you down and take it's toll.