My friend says I shouldn't talk to the guy I like...?

So I’m a junior in high school and I kinda like this guy in my chemistry class. He’s handsome and very sweet. Every day he sees me he says I look really nice, he holds the door open for me and he walks me to my hallway. We both like anime, he’s all into gender equality and everything which is great. So we’ve just been talking lately and he seems like a pretty cool guy. One of my friends, we’ll call her M, says that’s he’s really nice and awesome and just all-around a cool person to be around. So that made me really happy.

Now today I was talking to another friend of mine, let’s call her O. I was telling her about him, and when I said who it was, her eyes grew wide and she told me to avoid him at all costs and to not talk to him at all. She told me that apparently he stalks her friend K on Facebook and Tumblr, and he won’t leave her alone and he won’t respect her boundaries. That scares me, but the thing is, me and K used to be really good friends in 7th grade, but in 8th grade she kinda turned on me and wouldn’t talk to me and called me a b**** behind my back and stuff because apparently I was talking bad about her, which I wasn’t. So when O said that he was stalking K and stuff, I don’t know whether or not I should believe that because K made up a bunch of stuff about me being a backstabber and stuff back in 8th grade.

I don’t know whether or not I should believe M or O. From what I’ve seen from him so far this guy is pretty nice. I kinda like him and maybe would want to date him in the future but I don’t want him to end up hurting me and stalking me like he apparently did to K… I asked some other people and they told me I should be careful but I should talk to him and I should form my own opinion on him instead of just listening to what others say about him. I’m not gonna jump into things immediately though, I’m gonna talk to him and get to know him a lot more before I actually get in a relationship with him.

But what do you think I should do? Listen to O and K even though K isn’t a very trustworthy person, or continue to talk to him? Thanks for your help!