Advice?

Okay i been with my fiance for 3 years now we have been on and off so we did date other people and i cheated on him in december. Im not saying it in a good way i was just lonely he would go mia for 3 days at a time always stand me up etcc.... So still till this day i still get accused of doing stuff im not doing all i do is work or be with him. He proposed to me in june and i still hear this why give me a ring then? Our relationship would be so much better if he didnt do this. Im only human and i make mistakes just like he did but i dnt bring it up all the time like him.... Shouldnt he had let it go by now its about to be a year. It stresses me to the point when i cry because i dont do anything wrong at all ugh