My Husband Had Seen His Ex Fiance After 33 Years

My husband had seen his ex fiance after 33 years 6 months ago at a wedding with mutual family and friends he spoke with his ex fiance there and he came home and told me that he would like me to meet her and her husband and I was feeling very uncomfortable about that meeting because of him having an intimate relationship with her. She wanted to become Facebook friends with me and she wanted to have dinner once or twice a month with me and my husband and her husband and become great friends. I told them I felt very uncomfortable about this and I did not want to do that. He has not delete her messages and I don't understand why? What is he holding onto? He did think it would of been ok to meet her and her husband with no problem?