Nervous he will leave me

I've been with my husband for 11 years and found out last year before covid he had an affair for several months and fell in love with the girl. We have three kids together and I think that is why he decided to stay. I realized I had kinda been on auto pilot with my marriage and I've tried to fix that over the last year. He still works with her though and everyday I feel like he's going to leave me and every day I am scared he's cheating again and I'm not enough.... I don't know how to deal with these negative thoughts