I'm going to try to put this from your friends point of view, because I feel I was kind of there 10 years ago, and sadly I am no longer in touch my former 'best' friend who I had been close to since university.
Our relationship was initially based on a lot of drinking, partying, city breaks, going to the theatre... you get the picture. We both had slightly dysfunctional childhoods, difficult Fs but close with Ms, so I think that played a part in our friendship as well. We both suffered with depression at certain points over the years, or perhaps always but just more or less visible at certain points. I met my DH when I was 24, and I suppose it seemed plain sailing to anyone on the outside, although I certainly had my ups and downs, and getting pregnant when we decided we were ready wasn't instant, it took a couple of years of trying which was hard when everyone else around us seemed to be on baby no. 2 at least. Friend also got married, but it turned out unhappily with no children and I was as supportive as I could be (I think) but she moved back to the support network of her family which was a long way from where I lived. I think even before then we had drifted apart.
What I found hard was talking to her honestly about how I felt - the postnatal depression, the imposter syndrome with being a mum, and quite often the desire to just run away (I didn't find parenting hard, just mind numbing and frustrating most of the time) - when I knew she really wanted to have that life, settled with a husband and children, and a job I quite enjoyed. How could I complain about it when I really was incredibly lucky to have it?
It didn't exactly come to a head but I do remember a phone call when I think I was a bit short because we were on our way out, and then I'm ashamed to say I think I 'forgot' to call her back. I think she'd planned to visit but never followed up, and we exchanged Christmas cards then just stopped even doing that. It is sad, but on the other hand I think our friendship had run its course, and we'd both changed a lot. Keeping the friendship going had become an effort, without enough reward for either of us. Sometimes that happens.
I have another friend (from school) who, with her partner, decided not to have children. I completely respect that and perhaps because I've made no judgement on their decision, we're still close although we don't see/speak that often. I visit them with my 2 DCs and she's great at getting them playing board games or trailing round shops or parks with us, its just very chilled. Perhaps we don't have much in common but I find it a refreshing change to the child-centred relationships with 'mum friends'.
I suppose what I'm saying is perhaps its time to let go of your friendship for now, but try not to feel bitter about it because you don't know exactly what's going on in her life or inside her head. You feel like you need her support because you're having a tough time, but she might not have the energy or mental capacity to give you that right now, so she's pushing you away. But try not to lose all contact, because its those friendships from childhood that we might need to fall back on sometime in the future. My DH has friends from school who he sometimes goes years without seeing, then they hook up again, and he says they feel like family - he knows they'll be there for him if he really needs them. Give her a way back in for the future, don't cut all ties or end it in a finite way, and forgive her for the hurtful comments she's made as we all make mistakes.
As for your current situation, be kind to yourself, but try to be active and set yourself some goals that are just for you - not to meet a man or have a baby - but to learn a new skill or go to an exhibition or read a good book while you don't have a partner or children to worry about. You are strong, you are resilient and you do not know what the future holds. And you're certainly not old enough to think there's no hope of having your own family one day. Take care of yourself, and good luck!