Yes, it will pass but warning you another stage will be entered but hey that's just them growing up.
It is hard work at this age but soon you will look back and marvel at how fast they have grown.
When your youngest one is down for a nap get no1 to have a rest as well. I used to tell them it was not for a sleep but for a rest, we used to call it a reading rest, and they had to be on the bed or couch either playing or reading. Often they would fall asleep for a bit but it was enough to get them through. You could also take this time to have a rest yourself.
I really appreciate the suggestion but it doesn't work unfortunately. DD1 is past that point.

Thank you to everyone for their reassurance.
Kim, woah four.....woah. I take my hat off to you! x
1pj and olive, thank you for letting me know I'm not alone although I'm sorry you're going through it too.

Mel - thank you so much x

This afternoon they were both absolute perfection. They must have known that they'd broken me. Both are in bed and I'm enjoying a hard earned glass of wine. Here's to tomorrow! Cheers! lol xx