I'm sorry if this doesn't help you right now but I'll say it anyway in case it does or if it helps someone else.
I totally identify with this feeling you've posted, but I've come to question it. I'm thinking maybe because we've been expected to tolerate so much negative or bad behaviour, it's caused us to have unrealistic expectations of everyone else. We're there for everyone, so we expect them to be there for us.
Apart from the occasional dire emergency, or a best friend who you spend all your time with, or a partner, or an emotionally healthy family member - I don't think anyone ever is there for anyone else. It's just us unhealthy people doing that because we have been brought up to feel it's expected of us.
Sometimes I think this is why people put up with a lot of crap from their partner just to be in a relationship, because that's mostly the only person who's there through good times and bad. So it causes people to not want to be single, even if the only partner they can find is a mediocre one. I came to the conclusion that the answer to "nobody is ever there for me when I need them" is to level the playing field by not expending all my energy on being there for others myself either.
Sure, I'll call the fire brigade if my neighbours house is burning down, but I'm not housing them until it's repaired. I'll respond to friend's texts and calls and I'll make the effort to check in with them myself, but I'm not available for that while I'm working, eating, meditating, sleeping or out with someone else. I'll reply in between those times, when I'm actually free. If all calls are drama, I'll change the subject after I've listened and given advice and sympathy. If that doesn't work I'll distance myself until the drama is over.
I didn't used to be this way. I used to be all things to all people, but it wasn't doing me any good. Just meant I attracted users and made me ill.