Of course he was abusive, by any interpretation of the dictionary definition that you care to make. But the term 'abuse' is a very wide ranging, one-size-fits-all sort of word. If I call you an idiot it's abusive. If I held you prisoner for a week and hit you over the head with a hammer repeatedly it's abusive. One would understandably leave you mentally and psychologically scarred for life and cause you to shake in my presence, and the other (one would hope) would not.
Let's not get too caught up in arguing over semantics. Yes it was a 'relationship' of sorts, albeit a short, casual and patently quite unhealthy one and yes it was emotional abuse of sorts, technically speaking.
It's not that we don't think he was at all abusive towards you. It's that in the great scheme of 'abusive relationships' he wasn't that abusive, he wasn't sexually or physically abusive, it wasn't for that long, you weren't forced into it, you made no attempts to get away from it, nor did you even recognise it as abuse at the time, and so your reaction to it now, more than 16 years later seems completely disproportionate and more than a little emotionally unbalanced. The language you use to describe how you you'll react if you see him comes across as histrionic, catastrophising, and yes, sorry but rather attention seeking. You are highly likely to NEVER EVER bump into him in your life. How on earth can you know that you will shake and cry for goodness sake - you state it like it's an absolute fact. You say you dread seeing him but I can't help feeling you might actually be willing it to happen and perversely enjoying getting all het up in your own your own drama. How is it that you know he is living nearby again? You never said.
We are not telling you that you have no right to feel the way you do. We are telling you that it's not all together normal to feel the way you do and you would probably benefit from seeking professional help to manage the intensity of your emotions. If you could live with them in your head it would be fine, but to be running around externalising them by planning on telling lots of other people (and that is exactly how you made it sound in your OP) and wanting to message the man to warn him to stay away from you (you found him on facebook I assume?) and to be talking about labelling him in your community/social circle as 'an abuser' all because of some weird and emotionally immature shit he said when he was 18 is just NOT NORMAL OR RATIONAL OR PROPORTIONATE in the context of what actually went on. Can't you see that? 
You say you were ill and very emotionally fragile at the time, well it's possible that he might say he was emotionally fragile at the time, too. First year away from home, lots of social and academic pressure, learning to live in harmony alongside people who are not your immediate family, having sexual relationships maybe for the first time and learning to manage your intense emotions and insecurities in relation to that…it's a tough learning curve for lots of young people. Sometimes they fuck up. I'm not excusing or defending him, just asking you to get some perspective on it, now, as a fully fledged grown up.
My best friend's DD is going through something similar now, at uni. In a fit of drunken anger/jealousy she hit her boyfriend so he dumped her and will not have her back. This was months ago but she's still absolutely broken hearted and very bitter that he won't give her a second chance. She's struggling to keep it together and concentrate on her work, feeling extremely lonely and socially isolated and I am sure that comes across in an awful atmosphere as they share accommodation too. She did a stupid immature thing, she acknowledges she was wrong, she's living with the consequences, she's not a wicked person or necessarily a lifelong abuser in the making, she's just an emotionally immature kid who screwed up.
If he pitched up in her life in 15 years time when she was a more mature, non-abusive, happily married woman with a family and started slurring her all around the town and sending her messages to keep away from him when she wasn't even aware of his nearby presence in the first place I think my sympathies might lie more with her than with him.