I resent my family for being fat
Why would you resent something that they have no control over?
It's not that they're fat that bothers me; it's that their lifestyle is unhealthy. It makes me so embarrassed when I see them now.
I understand your concern for their lifestyle.  However, you shouldn't be so quick to judge them for it.  There may be underlying health or psychological issues driving that behavior.
I'll just think of it as a way for them to realize how hard their lifestyle is on me.
I think that you should try to be more understanding of your family members. I think that it is rude to judge others that harshly.