Sleep regression

My son went through the exact same thing around about the same time...perhaps slightly earlier. Hard to remember. It is a phase from what I can tell.

My only advice is to spell out exactly what you are going to do, then do it, then once the tantrum starts to reiterate what you said was going to happen.

Ie.
"We are going to ready 3 books and then it will be naptime" after book 1 I say "that was book number 1, you may pick out book number 2" same for book 2. At the start of book 3 I say "This is book number 3, after we finish this one it is going to be naptime. So, after we read this book what time will it be?" (MY son now responds quite happily "naptime"). After book 3, "that was book 3, it is now naptime" He would (and still sometimes does) start to throw a tantrum. "Mommy told you we would read 3 books and we've read our 3 books and it is now naptime" Take him to bed.

Follow through every day until he starts to get it. DS will now generally toddle off relatively happily to bed or only throw a wee tanty that lasts about 30 seconds right as I leave his room.

It's not fun though, I agree but having that set plan made it clearer in my mind what was going to happen and hopefully did the same for DS. I felt less inclined to cave into his demands if I had so clearly explained what was going to happen.

Good luck!