I am one of 4 children and my mother walked out when I was 16, the youngest was 10 at the time.
This was a shock to us when she announced on the day she left. My parents were never really around as they worked in restuarants so we didn't get to see much of them and "know them". Mum decided that she was in love with another man who had more in common with her.
What really hurt was when she told my dad as she left "you can keep the kids as they share your surname and tell them that their mother is dead". That was it, 4 years later, she managed to use a mutual friend whose daughter was my best friend to ask my dad for my phone number whilst I was at uni. She phoned and there were tears.
My sister and I do not have a great relationship with her, mainly because we think that she is not a good role model for us and my sister was affected the most as she went through teenage years with no female in the house (I was at uni).
We see mum occasionally but usually it's when she calls us. Mum seems to have generated money from thin air and keeps insisting on giving my sister £100 in cash as "pocket money" or to help her at uni. Sounds like compensation to me. She also treats us like as if we're still 10. I'm sorry but she's missed her opportunity to demonstrate her ability as a responsible and caring mother. She needs to understand that although we'd like her to be there for us, we don't need her in the same way as we did when she wasn't there.