Your last line there, explains it all. She probably cares for you a great deal, and perhaps did back then but she was overwhelmed by (I'm presuming anxiety/depression). It's a hard thing to deal with, both for the person suffering and the person who loves the person suffering.

I know it feels like she is the only person in the world, and it probably feels like you'll never find someone to love again. But that's just not true.

I don't know your exact mindset so I don't want to give any bad advice, but if you ever feel like you're at your brink, just dont do it. Reach out to the suicide hotline, to this sub, to me. We may seem like faceless strangers, but so many of us know a lot of what you're going through. I doubt anyone from this sub would write off what you say and ignore you, because we've been there.

With that said, it's time to work on yourself my friend. It's time to try and understand where this pain comes from, and how to fIght. I can tell you, watching the woman you love with someone else, day in and day out will destroy anyone. Jim from The Office said it best to dwight, about watching Angela, referring to when he watched Pam with Roy. He says (paraphrase) "This is a pain I wouldnt wish on my worst enemy", and I'm sorry you're feeling it.

I've been there. I know. I've felt the heartbreak, the sorrow, the emptiness, the betrayal, the why try and worthless feeling But it can get better. It will get better. Maybe not today, maybe not tomorrow. But eventually, if you work on yourself, you will build yourself so high that these bottom feeders who hold us down and tear us apart, won't even be able to reach you.