iseeyou you are lucky to be in such a position of ignorance.
I was in an emotionally abusive relationship for 7 years. His bullying and belittling and chipping away at my self esteem was so insidious, so subtle, that it became normalised and I simply didn't notice.
Suddenly I was 5 years down the line, feeling crazy from having my mind bent and convinced that everything that was wrong in my relationship and my life was my fault. I spent another 2 years tying myself in knots trying to change myself to make him happy until one day I stumbled across an MN thread and it was exactly like a lightbulb going off. Suddenly the penny dropped and I realised it was all him and not me at all.
It may sound incredible, but I needed to hear (read) someone else say it. Until then I hadn't been able to see the wood for the trees IYSWIM.
That's why all of these EA and DV relationships are always several years long - because the abusive behaviour starts slowly and builds up and up until the victim doesn't even trust her own judgement to tell the difference between black and white.
Obviously, if I'd realised my ex was an abusive prick early on in our relationship, I would have shown him the door. Hindsight's 20/20 but I was quite young when I met him and didn't know the red flags to look out for. Luckily I do now and will never be with someone like him ever again.
But it's having been through it yourself that makes it so easy to spot in other posters' threads. Some of the behaviour is so classic, if you know the signs to look for, it's like they all read an abuser's handbook or something.