Getting back but cheating by GF

I was in relationship for a year with a girl..she is working as a lecturer currently…I loved her too much..we were to going marry in within next 1-2 months...but suddenly we broke up….during break up she developed a relationship/friendship with a student and totally avoided me..after two months of break up she approached me.also i had strong feeling for her but i avoided her...on that day secretely i reached her hostel and called her it was 9pm time...she was not at her hostel...i told her to reach within few minutes at certain place and i was waiting her by standing on a road side far from that place..and was confident that she definitely will come on bike with her new friend and exactly same happen..she was dropped by her friend before that place...she called me and i said her i am infront of u...she shocked and started saying that i dont any kind of relationship with him...just he was supporting me mentally and we used to meet once a day and used to be busy on phone at least 3-4 hours a day.....but we dont have any relationship...i told her not to meet him again if you want to be with me....and exactly after the same day...i caught her in the morning roaming on his bike.....now she and her parents are approaching my family for marriage....what should i do....i am very confused.

Well you definitely shouldn't get married while things are so confused. You don't trust this woman and things won't get any better just because you marry. You need to have some long deep and honest conversations about what you both want from each other - it might be two very different things.