Don't beat yourself up, you're only human and you're grieving. That should be acknowledged and respected.
Why not consider taking a few days off from fasting and possibly everything else (if you can swing it) and just grieve, clean your emotions out. But go easy on yourself. Right now you need some serious tender loving care. Do something sweet for yourself to consciously validate your self-worth. Give yourself a little love. Pamper your spirit. Rest. You deserve it.
Then when you're feeling lighter, simply begin your fast again. If you choose not to take a few days off, just begin your fast again whenever you feel the time is right for you.
You haven't failed. A boulder fell on your head, but you've not failed. (Failing as in breaking your fast in the worst possible way...) The only time we fail is when we give up and abandon our endeavors completely. You've not done that. You're just staggering from that boulder, which is a normal reaction. Give yourself some time, take a breath and begin your fast again whenever feel ready.
And take good care of you, focus on yourself... You need you, right now.