Open Question: My husband denies having an emotional affair with his ex girlfriend, am I crazy?

I have been married for 20 years and with my husband for over 22. We have an 18 yr old son in college and a 15 yr old son at home. My husband had a close relationship with a girl in and out of high school. She broke up with him to be with her current husband. That was many years ago and 4 years before I ever came along. 16 years ago, she tried to be-friend me. We live a few hours apart, so she would call me on the phone. I was willing to be nice to her. Then one night, I caught my husband up on the phone with her (after we had gone to bed together). I told him to end the relationship, which he did. Recently, he discovered Facebook. He saw her on another friends list and sent her a message saying he always thought of her fondly. They had a back and forth messaging session, until I found out about it. She wrote to me and tried to make it seem like they were only friends and I was blowing it all out of proportion. Again, I said it needed to end or risk our long marraige. Last month, I felt that he had been acting strangely. I looked in his wallet and found a debit card from another bank(not ours). I confronted him and he lied and said it was only a bit of money so he could buy christmas presents. Again, not ok. Then one day, he made an odd gesture towards something in our home, I later looked there, and found a large amount of cash in envelopes from that bank! I confronted him and he wouldn’t tell me where it came from. After threatening him with throwing him out, he finally admitted that the ex girlfriend had set it up in an account for him. He claimed it was to help our family (times have been hard but not that hard). I told him that he needed to end the relationship forever. Also, if he wanted to stay with me, work to rebuild my trust which was now totally gone. I have not seen any effort to contact her and end the relationship, and the only effort to rebuild our relationship has been continually telling me he loves me. Is that enough? Not for me. What advice do you have for me? I don’t want to go through a messy divorce and hurt my children too. They are big, but still. I have a great thriving business and tons of wonderful friends. My self esteem is not an issue. Please help a confused woman…