Said I'm gaining weight!!!?

I was diagnosed with anorexia in march when I was in the hospital for the second time in 2 months, I haven't seen my grandparents since April and I saw them 2day and the first thing they said to me was that I was gaining weight and need to cut down on my food!! I can already see some of my old feelings coming back! I want to starve myself again and I can't stop crying! I managed to Handle gaining a few pounds but since they said that to me I feel like no matter what I do I can't make everyone happy!! What should I do? Also my parents are booking a holiday and are refusing me to go with them unless I gain weight because they don't want me on the beach with them :/