I didn't realize it had been that long... sorry! However, the general rule is 1 month of DBing for every year you've been together, which for you would be between 9 and 17 months, depending on whether you use your meeting date or your marriage date.
Regardless, I agree with you, you need to make it clear you are done with her. STOP doing things for her! Mowing the lawn and doing the dishes is doing nothing to save your M, in fact, probably the opposite. Do not mention the anniversary. What helps me is to try to imagine the roles being reversed. Say you believed you were DONE with your M, you were very interested in OW, and your W meant nothing to you, at least not in your concious thoughts. Would your W coming over and doing your dishes and laundry for you make you attracted to her, or just pity her? You might smile and say thanks, but would it change how you feel? How about if your W started ignoring you, moved on, got her own life, and started dating other men?
