Cheating spouse

So last night I found out on my own that my husband was sexting a friend of his (the girl he told me not to worry about 🙄) the whole beginning of our relationship. I had a gut feeling this whole time and he said there was nothing to worry about and that basically I was crazy and I believed him. He was still in contact with her and had recently spoken to her (earlier this year) and said he missed her and was thinking about her. Confronted him when I first saw those and he said it was in a friendly way then last night I said obviously it wasn’t friendly and he meant it in the way it sounded and he didn’t have anything to say to that. Now my question is has anyone/anyone’s relationship ever came back from this? The sexting happened in 2017 and haven’t seen any sexting messages between them after 2017 recently but all I can think about is those messages he sent her while we were dating. I’m just so angry, and hurt by him at the moment I don’t know what to think. However I do still love him and want to fight for what we have and not have our 4 years go to waste if it can be salvaged