It really is beside the point how long he was there for. He should have known it was against the rules his party proposed, and which parliament passed into law. The only steps he should have taken was to demand the party be disbanded, and to bollock all those attending and/or organised it, including his now wife.
From illegally suspending parliament, lying to the queen, attempting to get one of his mates off the hook, to attending at least two parties (that we know of) to allegations of islamaphobia. That's his record. And I haven't even exhausted the list of his misdemeanors, lying and law breaking.
For God's sake go, is the least he should do.