Happy and sad please help?

I used to really like this girl, well call her amy. Now I REALLY like this other girl, well call her izzy. The feeling was mutual with both girls. Lately,ive been texting izzy EVERYDAY and its so great because I totally have feelings for her and vice versa, but I feel reallybad because I dont like amy that way anymore and even when I text amy now she wont respond...please help!