Dealing with a negative family

I feel that I have grown spiritually thus becoming naturally more and more positive every day, however my family are very negative, and although I do not live with them anymore, every time I see them or speak to them, their negativity affects me and it gets me down.  I love my family and know that they need my emotional support but I feel that every time I speak to them it affects me, making me feel emotionally and physically weak. Sometimes I feel that I should avoid talking to them, but this feels wrong and makes me feel guilty. What should I do?