My childhood to adulthood friend likes me

We were born six months apart, and we've literally known each other for 20 years now even though we live hours away from each other at this point in life. He high key has a crush on me, and he is becoming more and more obvious about it as time goes on. I honestly don't know what to do with his feelings sometimes. My dad told me that if I have to truly question and agonize about how I feel, I probably don't really truly like the guy. Well, that's the boat I am in now. I feel like I am afraid of hurting him, but at the same time there is no way not to hurt him if he decides to tell me his feelings very directly. It's not like he isn't attractive to me in some ways, but I really feel like there are a lot of things about him that would not work for me in a romantic relationship. Anyway, he told me that if I got a boyfriend, that he'd kill the guy/ intimidate the guy for years and yeah.....he was joking but, I was like gosh that's horrifying..... I'm gonna have to burst his bubble though. I'll probably find a boyfriend at some point in the near future.