Utterly overwhelmed and torn

My husband and I have been together for almost 17 yrs, married 13. He had two children from a previous marriage that are now grown and pretty much on their own. Youngest one is a senior in college. We raised them as their biological mother was not always in the picture. We started having issues about 5 yrs ago. We got caught up in life, kids, parents illness and grew apart. Work and his hobbies seemed more important to him than me. I thought things would get better when my youngest went to college and my father passed. We would have the house to ourselves we would have more freedom to do things together but we only grow further apart. I attempted several times to get him to go to marriage counseling and he refused. I was always made to feel like my feelings weren’t valid, I was just crazy you’re having an emotional outburst and I was never important enough to be put first above his job or hobby. He’s a musician. But has a regular job day. I started doing things for myself, time with my friends and exploring new interests without him. He finally agreed to go to marriage counseling and It did help. He changed so many things and I had begged for him too all those years. I was grateful for the change but I have built up such a wall and don’t know how to except them. I don’t trust that they will stay. I stayed closed off and distance fir fear of being crushed again with broken promises. I then developed a close friendship with one of our mutual friends and he was my outlet, shoulder to cry on and escape. We had an affair and fell in love. We have always had an attraction and bond since we were 13 but we’re just friends until the last few years. My husband is now aware something has gone on between us and we are in turmoil. There is so much more to the story than this but I can’t take anymore time right now as my every move and conversation is being monitored. I know I have done a terrible thing and I’m very ashamed. I Just need someone to listen and help these overwhelming feels get better. Thanks for letting me rabble a little bit.