Exes and Ohs

My ex from nearly 2 years ago added me back on Facebook a couple of days ago...he changed his name and he's cut his hair since we last spoke, so I didn't realise it was him at first.
We got talking, and he started flirting with me again, telling me how much he's missed me and that he wants to meet up again and see if the spark is still there, and he's texting me loads telling me nice things. For example - I texted him saying "flattery will get you everywhere" and he texted back, "and so will your good looks, babe ;D"
I'm debating meeting up with him - I mean, what's the harm? - but I'm worried that my most recent ex, D, will find out, and get hurt, even though it's just going to be a casual meet up if anything.
I really don't know what to do...