You're on the path towards strong, independent womanhood. But you've been through a lot of upheaval over the past year or so, so it will take a bit of time for you to adjust: you're only human! It's perfectly understandable that you're feeling hurt by your ex's rejection. She promised to marry you for better or for worse; for richer or for poorer; in sickness and in health... and then as soon as you told her you were in pain and needed her help, she decided that she didn't really mean those words after all.
It sucks. Awfully. My ex did the same thing to me too, and it broke my heart.
But you know what? Eventually, I figured out that my pain was being driven by my own neediness. It was caused by the fact that I felt reliant on him for his love, support and approval, and when he withdrew those things I felt hurt and betrayed, because I still felt like I needed and deserved those things and it was unfair that he wasn't seeing to my needs like he'd promised he would.
So the problem was one that I could do something about. Because the minute I decided to stop looking towards my family for the things I need, and to look within myself instead, I started to recover from feeling so awful. I realised I didn't need that loser for anything, least of all my self-worth and self-respect. I can and will do it myself if I have to... and the right person will be attracted to that inner strength and self-reliance and will respect me all the more for what I've achieved. I won't lie to you: it's a painful process and it does take time. But as soon as I started looking within rather than without, I started to recover from the pain. It can and does get better: you just need to start letting go of your ex and stop expecting her to fulfil your needs. You are your own lifeboat.
As for your daughter, it definitely sucks right now that you're seeing her so infrequently. When my folks divorced I also only got to see my Dad every fortnight, so he made it a special treat for us every time we went there. He'd take us to the movies; restaurants; theme parks; weekend braais; Jo'burg zoo; the Bunny Park etc. so we always had something fun to do when we were with him. So if you see her less often than her mother does, you can make the most of each visit and spoil her when she's with you so that you become the 'fun' parent, and Mom becomes the boring one who always tells her what to do.

Then when you're in a better position and more established in your new life, you can get a lawyer and fight for more time with your daughter - who will of course want to spend more time with you if it's always fun to do so. You'll have more time with her, and she'll have the advantage of having a wonderful relationship with a much happier version of you.