Ignore his message; he's looking to see if you will take the bait he is throwing you. He has contacted you for a reason and those reasons are not necessarily good ones. You should not engage at all with him and delete his number.
There are other people out there who share the same interests as you; find them.
I'd be also advising you to look at Womens Aid Freedom Programme as abusers can and do take years to recover from.
That's not a definition of friend that I recognise.
You liked aspects of him, then you found out more about him and concluded that not only are you not especially compatible but he is harmful to you. At that point you walked away, dismissed him from your mind and protected your boundaries. Good.
I think what you're doing is getting nostalgic for the aspects of him you liked and trying to ignore the rest. You're trying to bring back the 'potential him' you created in your mind before you got to know him.
This can happen with friends you 'grow out of' too, genuine nice people who've just changed, as perhaps have you. You liked who they were but have to recognise they are not that person any more. It's a normal process. Onwards and upwards.
I have done this. I was an idiot. It took me a long time to realise that the person who was so horrible to his girlfriend (me, but I was no longer his gf) was someone not worthy of my company. Eventually it dawned on me when I realised I was feeling very protective of an acquaintance he was thinking of asking out. I realised I didn't want him anywhere near any woman, especially one I quite liked, and then I asked myself wtf I was doing hanging out with him myself, and then I stopped, and then I realised over time that what he did to me was abusive and I was an idiot with no nous and no self-esteem. He might be the sort who is only nasty to girlfriends, maybe he would be nice to you as a "friend", but you know better and should stay away.