Karan, dont you think you need to convince the girl too? Since you said you were going to surprise her with the visit and you are more interested in her. Girls these days have become independent & since she was in a bad relationship before she could be a case of 'once bitten, twice shy'. She's educated too & capable of supporting herself & her son all by yourself. Also, her son would be her priority, so you need to try and get along well with the son too!
I suggest you visit her first, hang around with her & the kid and take it from there. Don't let yourself in for heartbreak. And more importantly, find out how she feels. In India, you just dont marry a person, you marry the family! In case you get married, how are you going to deal with your parents? Do you think its right to make her go through the hassle of convincing them? I suggest you convince your parents first and do not be scared of them.
Just my two cents

All the best!