Changing for the Worst

I think Im changing as a person, and not for the better. If you asked me who I thought I was 5 years ago aside from anxious and panicky I would have said Kind and Patient. Thats before my depression really started. Now I dont know who I am. Sure i had incredibly low self esteem and i was insecure, but now I feel completely different. When Im not depressed or numb Im just not the same, and I dont like who it is. Im cold and shrewd. I snap at almost everyone for the dumbest things, and when i dont out loud i have a strong urge to do so. Im quieter than i used to be and Ive always been quiet. When I do talk I sound just cold and annoyed for no reason. I hate being like this. I hate seeing hurt or annoyance on peoples faces when I snap at them or say something crass for no real reason. Ive even caught myself being short with my fiance and it makes me feel terrible. I dont want to be like this. If Im going to suffer this state of mind I dont want it to be taken out on anyone. I want to be my old self but more and more its getting harder to remember who that person was. How do I work on this. Ive never had to work on how I treated others before because Ive always been kind and soft spoken. I just dont want to be like this. I dont want to be mean or rude to anyone. Its like Im becoming as a person on the outside as bad as I feel on the inside and I hate it. It just adds to the feeling of hating myself that I already feel growing more and more.