My bf of three years cheated , need good honest advice

So my bf of three years admitted to me that he cheated on me and that he hid it for two months and he felt so guilty about it that he had to tell me the truth what hurt the most is that I know the girl it’s an old co worker he kept in contact with from 2 years ago I knew they stood friends after he left his job and I never felt like she was a threat to our relationship issue is she’s 10 years older than me I’m 20 years old and my boyfriends 22 , I’m trying to be positive and get past this but the fact that he cheated killed a lot of the love I had for him because he’s actually a really really good genuine guy this is the first time he’s ever done something this bad we’ve been so good and happy for three years till this happened and everything is so bad I have little hope in our relationship and it just doesn’t feel the same some days are good and I’m happy and some days what he did haunts me and I don’t wanna talk to him I love him very much I want to make it work but I’m just filled with so much disappointment because he’s not the type to something like this. I lived with him for almost two years so I know him well. I just don’t know how I can get past this heart break is the worst feeling ever I wouldn’t wish it on no one another thing is her job is a 10 minute walk from my house and it’s been so hard not to go to her job and fight her so it’s just a bunch of mixed emotions going on and I don’t know what to do and how to get past this craziness