We're 7 in the group.1 is getting married in december.Every1 is included in the entourage 'cept me.Should i go

I felt i was not included coz im the only fat girl in the group and the bride is on a tight budget. I can afford my own gown if she thinks she'd spend more on my gown. I treated them as my closefriends since highschool but i feel they treat me differently just coz im fat. they criticize the way i dress, how bad my body looks in our pictures, laugh at me. My ex bf in highschool got married and i was the only one he didnt invite among our group. I only knew about it when we went out and they were talking about their gowns that day, how happy they were. and suddenly i realized im the only the guy didnt invite when the rest of my 6 girl pals were there. Why did they not tell me about it. This is hurting me a lot. What should i do?