oh goodness - I remember a totally illogical feeling of no self-esteem when I was suffering from depression about 15 years ago. But I have earned it now, because I know Ive worked so hard for my children, and made huge efforts to grow up, and get rid of stupid habits I had in my 20s.
Not sure what is the best way to shake oneself quickly out of it. But you are a single mother of 4, aren't you rickman? so by definition, you must be a high achiever. (I am just facing final financial separation from dx, and I too have 4 children, and it is looking pretty daunting, I can tell you)
There is no need to feel down about just speaking to a man. You aren't making yourself cheap, you are doing a sensible thing in looking for a partner.
I think it is really hard to get back on the flirt circuit after a divorce. It is all so much more complicated than it was before! I really like the idea of being married again, and yet....my freedom is good too. Also, most of the men I flirt with, I pale at the thought of introducing to my children.