Age gap

I'll start off by saying I'm 16. I've been talking to a guy in his late 20s. It sounds horrible already, I know. We're only friends, but he's expressed interest in being more in the future once I have my life figured out. He claims he's willing to wait to make it work, and that he is willing to visit and overcome the distance. He's the only person (*yawn*, I know) that understands what struggles I currently fight at home, because he went through them himself. We're great friends and I love talking to him. I wouldn't actually mind being more when I'm 18. But I understand that an age gap this big when I am so young is a legitimate issue. What signs will there be if he turns out to be a toxic person who is just manipulating me? Should I keep my distance, or maybe forget about it completely? Is it possible he's just using me or trying to manipulate me? Or could it really be something that works? What are y'alls opinion?

Update: Thank you all for the honesty, I really do appreciate it. I agree completely with what most of you are saying. I just wonder if this is something to confront him about? Or if I should leave it alone until he brings it up?