I think your sponsor has given you good advice. Your priority should be working on your 4th step inventory and your program. If you have taken the 3rd step, then your life, including your love life, is no longer your business. Is your Higher Power running the show here or are you running the show here?
We can only think a single thought at a time. My suggestion is to remind yourself who is in charge and to say the serenity prayer and the 10th step prayer (Thy will, not mine, be done) whenever thoughts of this relationship surface.
If you really want sobriety, I suggest you heed the warnings about staying out of new relationships during the first year. When those warnings are disregarded and those relationships head south, folks often end up drunk. I also agree with KeithJ above; the sex inventory is critical to understanding past relationships and our future sex ideal.
Susan