Am i overreacting? *Warning long!!*

My so called "best" friend has been basically forgetting I exist lately. She was in a toxic relationship for so long and I was the only one that stuck around and was there for her when she needed someone to talk to. I was the only one around when they split up and would listen to her. For 3 hours I listened to her crying and it broke my heart because she didn't deserve to be treated like that. Anyway, a few months after her break up she sort of found herself again, striking up friendships with people she previously alienated because of her bad relationship and I'm glad she's been able to do this. But it's like in the process she forgot about me. This was a few months ago and when I started dating my then boyfriend she sort of remembered me and wanted to hang out again (before it was only once or twice a month and barely any other contact). She even made a jokey comment saying "don't forget about your friends now you're in a relationship". But when me and him split, she was there for me in the following week but after that she just didn't bother. It was really hard for me because I cared for him so much, I really needed a friend, I really needed someone to go out with to take my mind off it. But in the following four weeks from my break up I only heard from her about 3 times. Twice she said "we'll have to have a phone call tonight catch up" but never bothered to follow through and never apologised either. I get that she has a life but instead of offering a shoulder to cry on for even just an hour she's out clubbing, hanging out with people who didn't bother with her when she was in her bad relationship. One of the other times she contacted me was to ask for money, literally that was the first time I'd heard from her in days and it was to say "can I borrow some money?" Which I don't earn much so I couldn't so I declined. Although it's not the first time she's asked for money (I always decline but she keeps asking). Then when we met up for the first time in weeks she never asked how I was, she wondered why I was so down. Then again I barely heard from her until I told her I had her birthday gifts to give her and then she remembered to thank me for her Christmas card. We met up again for me to give her the gifts but it wasn't the same, I feel because when I needed her the most she was absent and that's really stuck with me since. I understand if she was busy or maybe she thought I had moved on but not to even check in on me, ask how I was without him. She said when I first split with him she'd take me clubbing but that never happened. And yesterday was the first time we'd properly spoken for almost two weeks she said we'll have a phone call that evening to catch up, I said yeah sounds great. The evening goes on and I don't hear from her, figures. So this morning I get a text saying "sorry I went out to (another town like 1 1/2 hours away) until 3am". Like okay if you knew you were going out you could've just text me saying you couldn't ring me or said we'll do it the following day but nothing. I'm still getting over my ex and it still hurts knowing my only friend (known her since we were kids, we're 22 now) doesn't seem that bothered about me anymore. I'm starting a full time job Monday and a degree soon but when I told her she just ignored me to be on her phone (like every time we meet up) and in response to me saying I'm studying law she says "you do know that's hard right?" Like uhm thanks for the support😂 am I overreacting thinking this friendship has run its course, I hate being second best and I don't want to stand for this again. Especially when the one person I needed wasn't there for me in my lowest point and even months before I even met my ex I was in a bad place feeling suicidal but again she didn't wanna know.