How do i ignore them?

If they've been doing this for 3 years, it's for one reason: they are sad and pathetic losers with absolutely nothing in their lives other than you, and they don't even know how to express that in a constructive way. They need you to make themselves feel "superior," but really, they are jealous of you in some way, and that's why they are obsessed with you. If you want to be a positive person, take that as a compliment. Smile or laugh whenever they start on you because you are the center of their world!