Years ago I used to be a happy person.

I'm almost 40 now and I think I've hit rock bottom. I'm not a shitty guy. I've never cheated and never intentionally hurt anyone. I'm a bit introvert and maybe too focused on my work but I've been the kind of guy who gave everything in his relationships. After 3x5+ years failed ones I've got to a point where I don't see the light at the tunnel's end anymore. I don't think I can trust another human being with my feelings anymore and I don't know how to make the pain go.   
The previous relationship I had the girl I was with for years cheated on me and I couldn't get over it. I got to a point where I was hating myself so bad and blamed myself and my incapacity to understand her and how we got to that point. With the help of friends I managed to get over her and in like 2 years I've decided to go back on the "market". I was so pissed on the whole cheating thing that it was one of the very first things I would discuss with everyone new in my life. I found this girl on Tinder 7 years ago who was amazing in many aspects. The problem was she was coming after some fucked up relationships and with a lot of mental baggage. Also and she was having a way of life that I could not deal with. She was releasing her frustration by having sexual relationships with every male she could find. So I said pas and moved on with my life but remained friends with her because she was a wonderful person in all the other aspects. In the next year she got a boyfriend and she settled back a bit, but it was clearly a rebound. She dumped him after 8 months and we started seeing each other more and more often. After all the conversations I had with her I honestly thought she was over the dark mood and decided to give ourselves a chance after a while. I was always a bit off by knowing her history but I've tried to open up as much as I could. We had 4 beautiful years of relationship. We got close, we were constantly traveling and I loved her with all my heart. But something broken in her when her grandpa died and from that point she slowly drifted from me. The next 2 years have slowly became just routine. I've tried to mend our relationship but I only hit walls and rejection. So, like a dumbass I am, I didn't fought anymore. I let her drift and I zoned out into work. I knew what will come. I didn't want her to leave but I also had no more power to fight. I also need to say that I was going through a rough time by myself. I have a health problem that keeps me in pain 24/7. Sadly, loosing her support meant loosing my will to get better also. I've started neglecting my health issues and make her go away from me even more. She didn't left tho...and I know she loved me more than anything in her life, but she is battling her own demons and we got to a point now where there is no turning back. She started accusing me of not loving her and I got to a point where I was not caring anymore. Then instead of leaving she decided to cheat on me. Let me put it this way....for her fucking with others never meant anything emotionally speaking and she always hinted that if I can we could have an open relationship....at least that's what she said from the beginning. It was just her way to ignore her depression and be able to function. For me tho sex without emotional involvement doesn't exist and I asked her at the beginning of our relationship that if she wants to go with others to just let me go, couse that will break me. She didn't and she broke me. I had 2 days where I was out of my mind. The anxiety and struggle was at levels that I never knew possible. I was considering all the ways I can make her hurt, I was so petty I wanted her to feel what I feel. But then I realized that I can't. I can't be that man the break her just out of spite. I spent time on thinking of the things I did wrong, on the moments when I was cold and ignored her, on the lack of attention and all the shit I did wrong. I realized that I really love her and I don't want to loose her and I told her I want to give ourselves another chance. She didn't say no but didn't say yes either. So a month and a half later we were still going through an emotional rollercoaster where she told me multiple times how much she loves me and came back home but she also hold me in a limbo and made me feel like the last person on earth. I've been discussing with her probably more than we've ever talked in these last 6 years. I've been telling her everything I thought and all the things I love and hate about our relationship. She did the same to a point but she also failed to show me that she really wants to fight for our relationship. I've started struggling more and more to function and I ended up giving her an ultimatum. She begged me to leave her a few days to think but after the first one I cracked. I could not stand the pain anymore. I told her that if she loves me truly as much as she says then the choice of fighting for us doesn't need more than a second of thought. I knew that putting pressure on her will only make her run but you know....hope dies last. Now she's on her way to come and get all her things from the house after yesterday telling me I'm the one and that she will never be able to connect with anyone as she did with me. We've built so much in the past 6 years and I love her so much that honestly I have no idea what I'm gonna do when she's out of that door. I am so hurt and can't stop from crying. 

Sorry for the long post but I've lost all my friends in time and I ended up stranded with no support and in need of venting.