I honestly don't know what's wrong with some people - be it so-called best friends, or worse than all - the dreaded out-laws.
To your "friend" that goes to class with you - you really need to turn it around - just say - stayed the same again - I'd be gutted if all i've lost is 2lbs and wasting all that money to come to class...etc, etc.
I wouldn't care if she stopped going and I had to go on my own - you've been there a while now, it would'nt be so bad not having company to go with.
It is clearly all down to jealousy. Whether you think she's was being supportive going with you in the first place, she's clearly now proving to be a pain in the butt - and obviously trying to put you down. You don't need that!!
You either need to have a good comeback the next time she decides to criticise ANY part of your body - but say it with a smile on your face. You don't want to lose a friend - that would be awful, so you need to be nice... even tho you probably want to tell her to STFU!!
I like it when people notice i've lost weight - I know we shouldn't care about what other people think - but it is a big achievement, and it is nice recieving compliments (especially when some people out there are quick enough to put us down.)
Keep up the good work - you are doing brilliantly!!
Lx