Do you have a Self-Esteem First Aid Kit?
I do. I have a huge cookie tin under the baby's change table, and I have special things in it like notes from the kids, a birthday card from a friend, love letters, an award or two, notes about nice things certain people have said about me, etc.
When I feel really spent I go through my tin and read, laugh, remember and kind of fill myself up again. Every so often I put a really special thing in my First Aid Kit, and I can remind myself that I am worth something to somebody.