Husband had an affair

Okay so, my husband and I have been together for 5 years, married 4, we have a beautiful 3 year old boy together! Well we had grown apart to the point where we felt like roommates, we didn’t even sleep in the same bed, he slept on the couch and I slept on a fold out bed! Well, I got sick, had to have surgery had a lot of complications, got sent to a different hospital, well the day I came home I found out my husband had been talking to someone else! Then the next day after he got off work, he moved in with this girl, he had only known her for 5 days, had really only seen her face to face once! Well, this went on for a few weeks! He came home after 6 days for 2 weeks left again for 5 days then came home for a week then left again and came home then left again and came home again for the last time after having a mental breakdown! He’s been home for a month now and seems to be completely fine but I’m having a hard time dealing with everything! Do you all have any advice? It wouldn’t be so bad, if I wouldn’t have seen messages between the 2 of them that I really didn’t care for!