Help with guilt

I was in a relationship over 10 years ago. I was 21 at the time and we had been together for over two years. We were good but I felt the relationship going a bit stale. I had just lost my job I loved to redundancy and I was starting a new job out of my comfort zone. I started the training for the new job with a small group of people. It was there I met another girl. I knew immediately there was something there between us and the more I got to know her the more I really wanted to know more. My relationship at that time was getting worse. I don’t know if it was because I becoming more detached or not, I am not completely sure. Then a few months into my new job we had a huge argument then we split up. It was completely out of the blue but it felt so easy for some reason to just walk away. I made the mistake of going straight into a another relationship with this girl I met at work. We got together literally the day after I split with my ex. That week my new girlfriend went on holiday. My ex at this point was messaging me constantly. Upset and making me feel guilty for just walking away. It was all making my head a mess and I was confused what I really wanted. I was a selfish 21 year old that was only thinking of himself. That week I saw my ex again after she rung me over and over on night and I fell for it. I had don’t something I would never have usually done to my new girlfriend in the very first week we got together. It was a mistake and I knew it immediately. I cut all ties with my ex. I completely cut her out of my life and continued my relationship with my new girlfriend. Over the next couple of months I found myself falling in love with her. We are now married. We have two children together and we have never been happier. I love her more than anything, she really means the world to me. It’s been 10 years now. Recently though I have had issues with anxiety and thoughts that come into my head of this overwhelming guilt of what happened all those years ago. I did not tell her at the time what happened and it just ate away at me over the years until I finally gave in a few weeks ago and told her everything what happened back then. I turned into self destruct mode and let it all out. She was upset as you would expect her to be, she was hurt and we had a rough time, but we still love each other and we have put this behind us. My wife has forgiven me. My anxiety is still bad, it’s a really tough time in my life at the moment that I feel so disconnected from life. I can handle the anxiety, I’ve beaten it before, but I have no idea how to beat this guilt of something that doesn’t even mean anything anymore. Back then when I was young I was a selfish fool but I have since learned from my many mistakes, I know I am not a bad person and I am not that same person anymore. I feel like I need some perspective on what happened and someone to just say everything’s ok, because all I want to do is torture myself over something that I can never change. I tell myself it was one week into the relationship with an ex you thought you still loved, that I need to let myself off the hook, but I just don’t believe it. What I did was wrong, I know, but do I deserve this level of punishment?