You can only do as much as you can physically and emotionally bear at any given time ..... as you say you have a busy life too, and people's lives don't usually remain static either - the support you were once able to give at another time may not be possible right now due to your own current circumstances.
If you genuinely care for this friend and want this relationship to continue, then I'd explain to her what you have said here: that you had left her alone, as, based on past experience, she'd often preferred to get her head together on her own. Point out that if you didn't care, you wouldn't have texted, and, without responses from her, you literally haven't got the time to keep badgering her in order to "drag the problem" from her. Additionally, you were worried that if you kept trying to contact her she'd feel pressured.
If however, you feel that she is too much of a drain and aren't getting anything from this friendship yourself (apart from angst, worry, and a feeling of obligation) then maybe the time has come to be blunter with her ? This could go 1 of 2 ways, either it'll wake her up a bit to the fact that you have been a great, supportive friend and she hasn't appreciated this - and she'll apologise for snapping at you, or, she'll go off in a huff. Obviously, you'd need to be prepared for either scenario.
But it certainly doesn't sound as if you've done anything wrong. TBH, she sounds a bit of a user, regardless of how sympathetic you are to her dreadful experiences of men.