Is there any way to get over your husband having feelings for someone else?

Me and my husband separated 4 moths ago. I was devastated and heart broken. I tried everything my power to get him and my family back but he continuously told me he wanted to be alone and not be with no one and I believed him. Fast forward to now I recently found out he was seeing someone else and was developing feelings for that person. We are back together he is still in contact with that person he told me they were just friends and nothing more and that she had feelings for him but he didn't feel the same way. Well turned out he lied to me and told me he did have feelings for her but that every time him and her were together all he could think about was us and how happy we were. What should I do? How do I handle this?