In this
sort of situation, it's always better to appear magnanimous. You
know, like when you must inevitably walk into her path, with her
man, you should have initiated the 'hi'? It will erase any future
awkwardness for that matter of fact and you could probably maintain
that 'goodwill/causal friendship', even if you reckon that a
relationship with her is impossible?
Like Devil had mentioned - shouldn't it be easier on your part to
get along with life, since you had classified her as someone who
'took advantage' of your kindness? 
Cheers
