Hi there! I am so sorry you're going through this--there is absolutely no excuse for "slut shaming". Before I address anything else, I want to say: you were single when you had both encounters, they were both consensual and the involved parties knew your intention. You did NOTHING wrong! That being said, it can be really crappy to have people at school, especially your own friends, judge you and make up rumors. One way way to handle it is to move on with your life and let the rumors die out. The more you feed them, you'll keep them alive, so to speak. This doesn't invalidate feeling bad about it, you're in the right to feel however you're feeling. I just mean, if you don't give the rumors or the people saying them any attention, and you just keep living your life without hurting anyone as you have, that's the best thing you can do for your own mental peace and most likely they'll move on from it sooner rather than later too. If you know you didn't do anything wrong, then that's the most important thing. Unfortunately, it might also be good to reconsider if these are the kinds of friends you want to have. Friends should be supportive, not the ones doing the judging and trash talking. If you feel comfortable doing so, you could have a conversation with some of them about the way they're acting and treating you. A good friend would not contribute to this situation, they'd be on your side.
We actually have an advice column that I think would be really helpful since it's a similar situation, give it a read when you get a chance:
How do I get rid of a slut reputation?