Crap Birthday

First Post on Mumsnet, although I've been a long-time lurker. So today's my birthday. As usual, just another crap day stuck at home. I wouldn't be exaggerating if I said this is the worst birthday I've ever had!! I always feel unappreciated. I don't ask for much but even on my birthday, nobody can make an effort just for this one day!
I separated from my husband nearly 2 years ago. I'm raising 4 children single handed with absolutely no support. Their dad isn't interested, and I know I could be considered one of the lucky ones that I do get money from him each month. It works out at £25 per child. Which isn't much when taken into consideration on the grand scale of things.
I've been in a (new) relationship for just over a year. However I keep having doubts whether I'm just settling. The guy means well but as we don't live together. I still feel like I'm alone and doing everything myself.
As for today, my youngest daughter had a friend's birthday party. Because her other friends were attending, and not wanting her to feel left out. I agreed she could go, and I'd do something for my birthday another day. So my partner arrives early afternoon, and not long after, he tells me he had left his wallet back at home. He had pre paid his train ticket (hence not realising until halfway into his journey). So, the takeaway plans (which were meant to be a small comfort) went up in the air. Cue the whack of disappointment which I'm used to, hitting me in the face. Another birthday, where I'm feeling letdown and thinking, why do I bother. I was used to my ex, not making an effort for my birthday. Now it feels like deja vu all over again.
I had spent all week telling the kids that I wouldn't be having a Chinese because there are other takeaways I'd rather have. What did I end up having to settle for.....!? Yup, a Chinese!! Who had to pay for it...!? Me, out of my birthday money. Because I didn't want to touch my bank account with it being the end of the month and all my direct debits about to hit. I struggle so much financially that I do go without so much to ensure my bills are paid and my kids have what they need. My partner did say he will give me the money next time he's over. But it's the feeling that I've had to pay out and pay out for something I didn't want that makes me mad but sad too.
I've spent the majority of the day in tears. Because I feel like I'm never going to be happy. I'm always used to being letdown one way or another. I know I shouldn't compare. But last year my sister went abroad for a few days to celebrate her birthday. Whilst for mine, im sat at home eating a crappy chinese!! I've received messages saying, "Hope you've had a nice birthday." But I really want to tell people "no it's been crap, and probably the worst I've ever had." I thought perhaps just one day in a year, people could make an effort for me, but as usual, I'm proved wrong. I'm not really sure where I'm going with this. I just feel I need to rant and convince myself that I'm not being unreasonable!?