It sounds like you are dong your all mighy best to cope with what's in front of you. I congratulate you on being a strong person and facing this emotional time. I'm sure it's not easy. I am suggesting looking at your priorities. Would you agree that your children need you, your love, attention and time and also most of all: yourself?
Sometimes we think we are indespensable but once we are out of the running things will keep continuing some way or other, just differently. I'm just saying that to make you realise what you choose to spend your energy on right now. What's really important? I'm suggesting for you to not overdo it please.
Would you be able to look at the volunteering side and say: right I need to volunteer my time to me now to give me piece of mind and spend it in a manner which will keep me going a gear down then before? Could you tell who ever organizes the volunteer side that you need to lay back for a while as you you've simply got to much on your plate? It's human and absolutely understandable. Whatever you are volunteering for they appreciate having you more when you have 'extra' energy to spare. And it looks like you don't quite at the moment. Academics: see if you can get some breathing space there as well. People will understand that there's so much you can do and possibly once you talk about it, a solution can be found. It's not the end of the world. I would think no one would benefit if you do start to plod on with chance of collapse. Do what you think and feel will be right for
you.
I've had a stressfull period myself and still have to watch my energy output at the moment. It's a precarious balance but what helped me a lot was to say to myself: right I'm sick of draining myself, worrying and getting tired. (I thought I could plod too and handle it but as a result I got sick anyway, so my body decides it's time to stop even when my ego says it's not
) I've decided now to 'let it go' and to have faith that how ever it would work out it would be the right way. I knew I had done all I could so that was that. I did my best. This decision made me feel lighter and more relaxed. Please watch your boundaries too and be patient with yourself. All the best to you in this challenging time. Take care and please let us know how you are doing.