is sex a bad thing?

So, like I've only had sex with 3 people who I was with and loved. But like everyone at my school thinks I'm a whore, because of some rumors going around.. I just recently moved to a new school, and no one knows me, I've only had 4 friends that were guys, 3 that are girls.. well 3 of my guys friends wanted to date me, and I turned them down, wel now they went around saying I'm a slut and a bunch of other things... 1 of my girl friends got mad at me and said I was a whore because I talk to too many people... I honestly don't feel like I talk to too many people... but all in all my question is having sex is it a bad thing? I'm 17... and I've only been with 3 guys who I've been with for at the least 6 months... what do y'all think?