tphillips, in many ways, going primal amongst a non-primal group of friends is similar to becoming an atheist amongst a group of very religious friends. They will be oblivious to reason while mocking you or being aggressive to you.
It is worrying to read that they criticize your dietary lifestyle, instead of encouraging you in your pursuit. Becoming Primal entails, I would think, and at the very least, commitment and motivation to improve your health.
The fact that you used to be 400 pounds, are working on getting healthy, and are currently getting that feedback from your "friends" should, I think, make you reconsider their friendship.