Advice Needed…..

I dated someone for a little over five years and was absolutely madly in love with this person. He loved me, but it was clearly not the same kind of love. He was good to me, and he took care of me, but he was never faithful to me and I first caught him cheating on me right after I moved in his house after about 3 1/2 weeks of dating. Had I not just moved in his house and had I not been to humiliated to ask my roommate to move back in that would’ve been the end of it but it wasn’t and this relationship went on for five years and it got to the point where it was an open relationship on his end only and he would go out every Friday night and the rule was that he was supposed to be home by 3 AM and I would sit at home or maybe do something with one of my girlfriends, but I never asked any questions because I didn’t want to know. Eventually, he started getting me to sleep with girls with him and, nothing against people that do this for a living, but they were prostitutes and they were girls that were his daughter‘s age…… fast forward five years he decides to stop meeting girls on Tinder and sugar. Daddy apps, and started pretending that he was interested in women to sleep with him…. It didn’t take long before he found the squirrel Julie that he actually liked and she cheated on me with her for nine months….. He then told me that he wanted to be with this girl Jolie….. I always felt like he wanted to be with anyone but me and for some reason I just wasn’t good enough…… well, we broke up and I was so devastated that I seriously tried to commit suicide and I still don’t understand how I survived….. It was an extremely tough year….. eventually I met someone and I started dating him, not because I loved him but because I was trying to get over my ex. When my ex realize I was starting to move on, he pulled me back in…… he is still dating this girl that he cheated on me with, but we hang out together a few days a week and sleep together 3 to 5 days a week…. Now I feel that I am no better than he is…… The worst part is that he is marrying this woman next week….. He says nothing will change between us….. he does not realize is that I am already dying a little bit more inside each day…… I have literally not slept in …, well, if I don’t sleep tonight, it’ll be four nights because I’m so distraught. I’m so madly in love with this man and he does do good things for me and help support me but at the same time he has always sort of just discarded me as a piece of trash. At 43, I had pretty much just given up on the idea I’ve ever finding anybody and spend every day by myself in my house alone… With the exception of when I see him….. I don’t know if anyone has been in a similar situation or give me maybe some pointers because I’m afraid that this story isn’t going to end well for me…