1. Using profane language in a TEXT is a sign of immaturity. I can understand such expletives used in a vocal setting in the heat of the moment, but in a text?
2. If you wanted an explanation why it happened as it did, you would have given some facts. So you only wanted to vent. Hence the stick and smash suggestion.
3. Now that you are talking facts, lets review:
a) Somebody in your empire attacked a neighbor. You have absolute crown authority, which prevents your direct vassals from waging war. There are 4 ways it is possible - war started before you enforced the law OR the vassal had a hook on you OR vassal had declare war rights in the vassal contract OR the one who started the war was not your direct vassal, but a vassal's vassal - as in, you are Empreror with a king as a direct vassal, and that king has a duke as a vassal, and that duke started the war. Working as intended, not broken by game design.
Another possibility, is that your vassal was involved in the war as an ally, and not primary attacker. But then you would not be able to join the war, unless you were allied to any of the primaries.
Still another possibility, is that you inherited a defensive war.
b) For abdication to stop the war, either the war must have been due to attacker pressing his claims on your realm. Claimant gone - no casus belli - war stops. Also works as intended.
It's okay to admit, you have little knowledge about how the game mechanics. Hell, I don't know them all, and I study them because I enjoy it. I suggest you stop acting like everybody owes you something, and learn how the game works.
