I would strongly suggest u forget about her, unless she chose to come with u. To me, being attached is nothing really. Either party can always choose to leave for greener pastures. But beware of the surroundings.

She could be 2-timing, or she could have missed the detail of letting u know of her status. But if she chose to lead u on, then clearly we know what type of person she is. Give her the benefit of the doubt.

Don't be so sad. There are greener pastures out there, waiting for u to explore. Have fun!!
