leaving toxic ppl behind?

long story short i was bullied by this group of mean girls a trio ironically enough.
they basically made my life horrible: made fun of me, excluded me, caused the break up between me and my bf of 2 years too (well i now realise my ex is a very toxic person anyway and i am glad he is out of the equation), they even didn't include me in any photos and left me out of everything making me feel isolated. They made me want to cry and get so angry too.
This went on for months on top of the whole breakup between me and my bf, in the beginning it was bad. Like crying and getting so ****ed off every day but as time went on and i put my trust in my true friends it got easier. They still continued their *****y ways and it still hurt me but i learned to ignore it from the outset. Coz yk as they say don't bleed in front of sharks.

NOW-- i saw 1 of the mean girls at a university open day and this uni is the 1 i really want to go to and is my first choice. i went with my parents and she must have gone by herself or something idk.
I happened to see her when i was eating food with my mum and dad on campus site and she was on a mini tourguide thing idk. She briefly waved at me and made the first move.
My parents had a bit of a moan at me for not saying hello first or making the first move. But-
1) it's awkward to just run up to someone in the middle of a guided tour that is moving anyway and strike up convo.
2) coz she and her little posse bullied the hell outta me and made my life horrible so i am not going to bother speaking to her.
3) i genuinely couldn't tell if it was her or not coz i have bad eye sight.

Since then i found out that that particular mean girl has also put down the uni as her first choice and there is a chance we will both end up at the same uni.
My parents are encouraging me now to get all pal and buddy-buddy with her even when they know everything that has gone on.
I don't want to particularly because
1) we are not on the same course even
2) i am not randomly talking to someone who doesn't like me and i don't like them.
3) i talk to whoever i want
4) the entire point of going to a new place is that you speak to new people yk

I told my grandma about this and she agrees with me and says that i have the autonomous choice to talk to someone or not. And that those girls are nothing but trouble and history will only repeat itself. she said the best thing to do is ignore that girl and focus on yourself and a new beginning. a new leaf.

Besides, i do have a close friend who is going to same uni as me anyway so it wouldn't be so bad and i wouldn't be alone on first day etc. And i'll talk to new people.

I am trusting my grandma and my gut but i am still stuck between my parents words and hers and my own.

What do you think I should do??????

much appreciated <3