Hey cuty121, I totally understand your situation as I am Hindu myself and know how family plays a BIG part in personal relationships.
I have been through what you are experiencing. My brother was dating a Bengali girl for 6 years (hiding it from parents and family), he finally decided that she was the one for him and came clean to the parents. Of course they were not happy with it at first as they wanted him to marry a Hindu girl. After awhile they realized that if they force him to end it with her and marry a Hindu girl, he will NOT be happy in the future. Needless to say, they got married and my parents could not be happier for them both, and they love her to death now.
What I'm trying to say is, at first they will no doubt be mad and will NOT understand, but you have to lay it down for them. Eventually they will understand that by forcing you to marry someone else will not be in the best interest for you or for them.
Hope this helps. Don't hesitate to email me.