I got cheated
So I was in a relationship for the past 10 years I'm 26 and she is 25. We were happy together we used to travel alot we both have good jobs and we were financially stable. I was doing everything to make her comfortable with me but 1 day we had a bit of an argument it was no man's fault we got carried over for a small argument. We were staying together I had been sick for some days and was waiting for the doctors appointment. She knew this and she continued arguing with me. I tried to stop that I said sorry for apparantly no reason then suddenly she said she is gonna stay at a friends home i begged her not to do that but she went. I was physically not fit to drive and go with her. Her friend was not at her home only her husband was there. They were also friends then he started comforting her and in that moment she forgot about me and had s*x with him. I feel completely betrayed next day she came back and apologized to me and told everything but it's just too much for me to handle. What should I do?
PS: I know this is vague but I'm in no state to explain everything and this happened 2 days ago