My son had slept for four hours at a time at night until about the same time and I became so sleep deprived, it takes me a long time to go back to sleep, that I did end up letting him cry it out. I only did it the first time that he did it at night until he got used to it and then started doing it until about 5 am so that he slept through most at the night at least. He now is almost two and he still wakes up at 5 sometimes but then there are many mornings that he doesn't get up until almost 9 when he's ready to be up for the day.
It worked really well for me but you need to do what you feel is best for you and your baby, both of you not just your baby because if your too worn out from a long night to take care of her the next day then getting up every time doesn't help either one of you.
Good luck, I know this isn't easy.