Should I still marry her?

Salaam brothers and sisters, I have a situation here and I would like some advice. Late July, I (M23) met a sister (F19) at my work place, I normally buy lunch from her, and just like me many other guys also buy lunch from her. We started talking in early August, I got to know her a bit well and I also fell for her and at least it still seems mutual, she asked me to introduce her to my mom of which I agreed. I told my mom about her, she's happy to see and so are my siblings and my dad. We agreed on engagement after that. Yesterday I saw one of my cousins who works somewhere just close to me, and some how I brought her up. He told me things i sort of expected from a girl in the market and how he was involved with her. How she had a crush on him and rejected her, how she once gave him a peck on the cheek and kinda got physical with him. He also said things have ended and he totally pushed her away. This made me want to end things and to call off everything but I also love her. She gives me comfort that I can't really describe when am around her, she compliments my masculinity. This love i have for her can't really let me bring myself to calling everything off. She brought me lunch just 3 hours ago and she told me how she wants to meet my dad. Now I don't know what to do. I don't want to marry a girl that has been kissed by my cousin and any other man that I know about, whatever I don't know about, I don't know about it. On the other hand I love her so much, I can't bare to see her sad over me after telling her to end things with me. What would you guys advice me?