I feel there is three in our marriage

I have been married for almost a year now…We are not young and both have been divorced. I have 3 adult children and he has none. We get on pretty good, I have known him him off and on for 50 years. But I am struggling with his ex wife…he has been divorced 6 years now…they had been together 10 years and going by what he had told me he liked/likes her as a friend. But he just couldn’t be married to her as she shows him up, corrects him and makes him feel stupid she is possessive and stuck to him like glue. He divorced her because they argues so much and because he brought in his disabled daughter home to care for her as she was dying and she was so jealous.
Any way when we got engaged she thought he was stupid and laughed at him so he tells me.We married a year ago. He told me she spent two years telling him why we shouldn’t marry. She lives so close to us. She wont be civil towards me…But my husband still has time for her…she messages him maybe weekly or more as he doesn’t tell me and its stuff about her or sends clips on some thing on facebook. When he goes out of town she phones him. I feel they might even meet up some where and spend time together. When he bought me a eternity he told her in one of their conversations…she had a go at him and said why did you do that…We live in a small town so we can bump into each other. The other day I was out walking and his ex was walking over the other side of the road…because she dislikes me I thought if I got eye contact I would say hello…because I am sick being upset…well she never looked at me …she messaged my husband and said she saw me and he might of asked her did you speak to her and she said " I have nothing to say to her"…yet she asked him to come to her house to mind her cat while she is away…but don’t bring her…ok she doesn’t have to like me but she could be civil…also my husband should back off and let her move on. He tries to please me and her why? He has told me “she is a friend I shouldn’t of married and they have similar interests” What really up set me the other day…is he went out side to talk to her on the phone and he was whispering and how he was talking was nothing like he speaks to me but he obviously didn’t want me to hear…I had planned for him and I to go away next week for a few nights as he has been under a lot of stress…at first he was ok about it but came out later in he has to feed her cat twice a day while she is away…I said why doesn’t she put it into a cattery…but he did say she asked if he could take her to the airport and pick her up which is 90 minutes each way…he said no to that. He tried hard for me to not go on this trip because of her cat. He has sorted that out by shutting the cat in her house with food and water and kitty litter for 3 days…so she has to say to him, “its her who has done this” guess what " he doesn’t stick up for me…I feel they both bitch. So this is why I say I feel there are three in our marriage…he is in the middle.