He's making me uncomfortable?

I've been friends with this guy for three years, we met online on an app called butter and we've never met in person. He's a nice guy but I only see him as a friend and I've made it clear and he's like ok. So a year after, I met my boyfriend... on tinder, we've been on and off since November. 
Since then, the other guy has gotten extremely protective of me. He's constantly telling me he's in love with me and he can treat me better than the other guy. I go for a few days not talking to him and he goes off on me saying that, I don't check up, he doesn't know who I am anymore since I got a boyfriend, he stalks my instagram, he gets upset that I'm with someone else rather than him. I've never led this guy on, I treat him like any other friend that I have but there are days where I can't keep in touch cause I'm busy. He has makes such a big deal over nothing. He tells me all the relationships he's been in since he's known me, mean nothing to him cause it's not me. That's another reason why I don't contact him often. I have no feelings for this guy whatsoever and he's like, I understand if you need to wait. He even named one of his kids he had with an ex after me, I thought that was creepy. I literally don't know what to do!