Smeggle, I do not know anything at all about the feeding tube and coping with that, what I do know about is not sleeping at night. There are many nights when I have been up all hours of the night, sometimes just sitting and trying not to think, other nights playing games on the computer or reading.
I have always meditated but found that my mind was not in a good spot to do this to relax enough to go back to sleep. I think that your body calls on all reserves that it has to get you through this time. I found as time went on there were afternoons that both Colin and I would lay on the bed and sleep for 3 hours straight.
Maybe you could try doing this if your little girl is still sleeping through the day. If she is not is there a friend or family member that could watch her for a couple of hours so you can take some time out, even if it is once a week or fortnight. I am not going to tell you to keep yourself doing things for yourself, because while I know that this makes sense it is near on impossible to think about.
Take each day one at a time and sometimes I find it easier to even break it down to hour by hour or even moment by moment. Certainly enquire about what support systems are available from your local council to help you. I know that you are in country Vic, and sometimes there is more available to you than in the city. Take care Smeggle, I am thinking about you and wish you all the very best.