@ Spookypitch so i met a guy once and immediately we didn't like eachother and we would always fight. But soon enough he fell for me and i for him. Even though nothing more happened between us and it was all a big mistake for a lot of reasons, we were talking for a long time so ill tell you how we transitioned literally from enemies to lovers. So he made the first move and texted me in a more friendly way than usual and I caught it and said it was all good between us. And it was very wierd cause it was a conversation only between us. We would continue to fight but it was more in a way where we both knew noone was actually mad and we were just teasing eachother. Although to others it looked like we were gonna kill eachother.
So with all this in mind, first of all if you find yourself in a position where it's suitable for you to be a bit more sweet and friendly, (when you two are alone), you can tell him that you actually think his a nice guy and see how he reacts. Then you can continue acting the way you did but when you talk, make it look like you joking/teasing/flirting more than trying to argue. Of course I dont know anything about your current relationship but i hope i helped a bit. Then if he likes you I think you'll be able to tell, because when your behaviour will change, he will act differently too in some way. But I think its very important to get to talk with him when you are alone. Even if it is in person or online