How do you end an affair with a married man?

Any judgemental people here stop reading and dont reply to this. I have been having an affair with a married man it started out as a flirtation in cl then became full blown. At first I liked having the affair its something new and thrilling. But now the guilt is here full blown I want to end it with him but dont know how to? We have a cl together so I dont want this to interfer with my schooling. So im in a predicament do I end the affair once the cl ends in 2 months? And should I own up and tell his wife in a letter, or face to face meeting that I have been sleeping with her husband? So confused if anyone has experience with this please do tell.