Maddog, you have a really long break. I have no idea how I'd cope with something like that. In the old days I'd have switched off completely, probably, but I find that having opened up and trusted my therapist I can't numb from that now. During the break, the lack of going to see her felt almost like a palpable thing in itself, if that makes any sense.
I honestly think it's reasonable that you texted him. I think any therapist has a level of responsibility towards their clients that means they're no longer in a position to take five or six weeks off in the same way as someone in a different profession. From what you've said before, occasional contact is his expectation, and I think it's only ethical to have that over such a long break at this stage in your therapy.
I can't decide what feels worse - the shame of having collapsed and called him when I have no right to and had promised myself I wouldn't, or the fear that he mightn't call me back, or the fear of what I'm going to say if he does, or the knowledge that even if he does, it will be a brief contact only, and there's still another 3 weeks...
I think you did have a right to. I'd go further and say that I think you had a responsibility to. A responsibility towards him as much as towards yourself. During the break, he's dependent on you to monitor how you're doing and take appropriate action, because he can't do that from where he is. Sending him a text and asking for a call is completely appropriate.
I know you found it hard to communicate during the last session before the holiday, understandably, because of how difficult things were emotionally. Can you plan something to say and note it down to refer to when he calls? I'd suggest in particular that you try not to spend most of the time apologising for contacting him. I imagine this might easily happen, but one sincere statement at the beginning that you're sorry to interrupt his time, and then once again at the end, is enough. Maybe if you had something written down and prepared, it could help?
Do you think you might be able to ask him for something which would help you get through the next three weeks, such as a weekly email, text or phone call from him, on a specified day? For me, being uncertain about when or if I'd have contact would in some ways make things worse. Maybe you could phrase it in a way that wouldn't mean rejection if he can't do that much, such as asking whether his schedule could allow for a little arranged contact - whether that's weekly, or a couple of times or just once during the remaining time - and leave it to him to decide about that.
At the very least, I'd explain how difficult you're finding it and ask for his suggestions on practical steps for coping. You may have already had that discussion, but I think it's worth having it again, to see what he says.
I'm really sorry for how hard it is to get through the time. I know that I feel so unsettled the whole time, I'm always in a kind of half limbo whatever else I try to do. I think all we can do is try to practise good self care and not be hard on ourselves. That includes accepting that you needed to contact him. I understand how difficult it is to contact someone on their holiday, but you have done the right thing.
Sending lots and lots of suppport to you.