I think I'm giving up on my relationship...

We've been together for almost three years now (on and off). I love her more than anything but I just can't depend on her. I feel like her love and support for me is conditional on how secure she feels. She's let me down amd hurt me so many times before but I think the other day may have made up my mind. I had a presentation for a three term project I was completing as a degree requirement and I was really important to me that she was there. We had fought the previous night because I had told her to hold a coffee for me. I was going to fet something out of my bag but apparently she felt like I was being belittling and manipulative and she felt embarrassed. I was so frustrated and I admit I didn't didn't handle it as well as I should have. I was beyond echausted and I had just had enough of her attitude over every little thing I did or didn't do right. I did tell her that I would really try to never embarrass her like that again but we ended up leaving on a bad note.

The next day I felt sick all morning because I pretty much expected her to not come to my presentation and support me. I even delayed the start of it and called her probably ten times and she didn't answer. I was honestly barely holding it together I felt so crushed, but I kicked ass and finished strong.

She had sent me a few messages while I was presenting. She didn't even remember the time it was was supposed to start... she said she had a rough night and "simply forgot to set her alarm". It started at 2 in the afternoon... She's not working, she's taking a term off from our school... she literally has no responsibilities right now. I have worked my ass off to pull my life together in the past year and I'm finally succeeding and I may even make Dean's list. I'm just so dissapointed that she wasn't there for me and I just dont know what to do.