I love you , I'm just not in love with you

Just last week my spouse said these words to me. It was like a slap in the face. It has been three years since I found out about my husbands affair with hi ex-girlfriend. We have been through marriage counseling three times and all without any resolution.

My husband seems to be one of those people who believes because he says he is sorry for his actions everything should just go back to the way they were before his affair. Now three years later it feels like we are still at day one.
I have wanted to leave the marriage several times but I didn't because I had hope that one day things would get better and we could begin to build a better marriage for ourselves. Now with him telling me he is not in love with me anymore, I feel like maybe there is no hope at all.
I told him being in love is something you have to work at and if you don't put in the work those feeling become unfamiliar and fade like a distant memory.
What I find strange is less than two months ago he was telling me how much he was in love with me and could not imagine his life without me as his wife. Now he feels only love for me. What is wrong with this man? I asked if he is having an affair again but he says he is not. It is something broken in him and he feels like he is just empty.
What am I supposed to do with this latest breaking news from him? When I tell him the marriage seems to be over he swears he does not want me to leave but how can I stay with someone so broken?
The past three years have been like a nightmare that I am not able to wake up from. There have been so many lies , so much heartbreak, and so many disappointments. Every time I start to heal there is always something from him that pulls back the scab to expose the womb again. I am starting to believe my husband has some kind of mental problem or he is grieving for his lost affair partner. Either way I am at the end of my rope and I think it is time for me to just walk away.