Don't allow anyone to change your healthier habits through guilt, frustration, or in order to please others. Family can be especially difficult to handle. No matter what, stand your ground. You will be successful.
I recently had this issue with my mom, who LOVES to lather on margarine, mayo, etc. After discussing the whats, hows, and why-nots of my eating habits, I was able to establish clear boundaries. That way, if she made an unhealthy snack, I stopped the quilt why I was not eating it or made my own.