^ what jgib said! You set the tone, you've already shared you've had some bad experiences. Leave it at that. Don't go too deep if you aren't sure of his intention; sometimes folks who seem okay turn out to be the ones preying on us when we are vulnerable, as you have already experienced. I had a dreadful experience (at least to me -- nothing bad actually happened but I felt I opened myself up too much to someone I didn't know) the first time I tried online dating. I then made sure to protect myself. I asked a lot of questions but didn't give too much away about myself. When I decided to meet for the first time, I made sure 1) two of my closest friends at least knew where I was going, 2) they were asked to call me if I texted them to say I needed to get out of there -- the plan was I'd go to the restroom and text them, they would call me once I got back to the table, and I would say I needed to go to take care of a situation with work, 3) I got there early to scope out the scene -- if he didn't look right, I didn't hang around. My online profile was very up front -- I have guard dogs, I am very self-sufficient, I was not looking for casual flings but friendship leading to something meaningful. If approached by someone who seemed after just sex, I set the scene right away.
This is a bit different for you because you know this person. However, if you feel the need to protect yourself, do so. It's your journey and no one can or should rush you. All the best and hope it is wonderful should you all get together!
