if the universe is infinite shouldn't it have experienced an infinite number of universe ending events? or is it that the definition of infinity used here excludes such events like there are an infinite number of odd numbers but 2 isn't in that set?
The universe has a finite age, about 13.7 billion years. So there has not been time enough for infinite events in our past light-cone.
There are rather few events in mainstream physics that are universe ending. Closed universes eventually implode, and if certain forms of dark energy exist they can cause a Big Rip where the universe expands to infinity in a finite time. But obviously observers cannot look back on them in their past. This is also true for other local disasters like false vacuum decay.