Relationships, particularly intimate sexual relationships, aren't something that most of us get over quickly. A year may seem like a long time but in the scheme of things it really isn't. Your sexual thoughts about her are understandable, particularly if the sex was good and wasn't part of the reason for the split.

I agree with the other posters, try some other social outlets, even if it isn't an active hunt for a new intimate partner; life happens, a new partner may come along soon, or not, but either way it may give you something else to help you get over these thoughts.