Do I leave one Relationship for Another?

I've been in my current relationship for almost 16 years. He's a good, honest man who loves and respects me. However I feel like I have been moulded into someone I am not. I allowed that to happen. I stopped drinking (I didn't have a problem but it caused issues with us as he doesn't drink) and I don't have any close friends to talk to as moved from home city. I do nothing with anyone but him. No shopping trips or dinners with friends. He doesn't work, has never really worked unless I hired him, which came with its own issues. and I've always been the provider and one who pays the bills as I make a good salary. He does give me some money each month but it's not enough and I struggle. Silently. Me providing isnt the issue though. I used to be such a fun, happy girl and now all I do is work and go home to him. I'm not unhappy per se, but I'm not loving life with him. But I care for him and we have had a great life travelling the world together. We moved London from Scotland 8 years ago and I feel kind of isolated. I do feel I bit controlled but it's very subtle. Never direct and never obvious but I know there are things I can't/won't do for fear of it being an issue and think over the years he's made me how he likes me to act. I comply I guess. Now recently I've fallen for my Ex whom I never got over even though we dated 20years ago. He was married at the time and after a few years of waiting for him to leave her, he never did and I left. We've been back in touch as pals for last 4 years and I've helped him get him life back on track. He's Ex Army and has some mental heath issues and alcohol issues however it hasnt stopped me falling in love with him again in the last few months so it's all quite new. I see his life is a car crash yet I love him. He makes me feel like the most amazing women on this earth and we laugh like I have never laughed with my SO. I feel free. I can be myself with him. Be the woman I used to be and I'm not judged for it. I miss her, that fun girl I was and am with him. I miss the happy me. Right now I feel life is just passing me by. He has a good job and has Family. My SO is from Abroad and has no Family here so I've never met his Parents or Siblings so life is very lonely, we never had Kids together as he wouldn't have kids as he didn't work and couldn't provide for them. The other guy, I met his Parents last week and I loved that small opportunity to be part of his Family. My Mum died when I was a teenagers and not close with my Dad so being taking on and made welcome by them meant a lot to me. He wants me to leave and be with him. He says he loves me and I belive him. We are good together. Do I leave a decent guy, break his heart for the chance to be free and happy? Even if this is a disaster I still think I would be happy on my own. Free. I feel caged just now, and going through the motions. Thing is, I have never really had to leave someone before. I don't even know how to do it and the thought of hurting him kills me. I don't know if I could live with he guilt but the alternative is I carry on with life pretending I am really happy, and stay back in the cage? It's a nice cage, but still a cage. I have absolutely no one I can ask or advice. As I worry too much what people will think or me. I was scared to tell my Sisters as I feel like I'd be telling them I am a failure.