Am really cross......

Is it normal to still be knocked back into obsessing and ruminating, mulling and wondering at this stage......I am coming up to 4 years out and NC aside from the occasional forced, unavoidable nod or hello in the street.....and STILL I can have these times where I think it is NEVER going to go...
I feel stupid that it looks like I am STILL holding on to a grudge when I see him (I realise I should not give a damn what he thinks, if he thinks anything) but because of how things panned out immediately after we had split for good (despite what appeared to be a reasonable split up conversation between us) what we both thought was about to become a friendship simply could not be, for me. Once I began to come out of the fog and when I discovered how quickly he had moved on after taking me to hell and back with his bullshit about needing to be alone, how much he loved me, and how sad he was.....and the tears, oh the tears. Literally heartbreaking for me. To discover he had just skipped off with another woman nearly did for me. And not for the reasons he would think, me being a jealous woman etc, but for the torture of witnessing his so called pain at us not working, Greek Tragedy drama performance, which I bought.....I BOUGHT. And was devastated along with him. I was waking up heartbroken wondering if he was ok, if he was going to consider counselling finally so we could one day be together when he had had all this time alone to sort himself out !!!!!
What a total shock to discover he was away with another.
I still sometimes cannot believe it. Because his pain was SO believable.
Anyway....where this has come from I have no idea. I just hope someone will tell me that this sometimes can happen....or is it time I was carted off to the funny farm ?