My neighbor lost her mom 2.5 years ago. Not to ALZ. She said It will take a bit to shed the lead suit you feel like you are wearing. Yes you will be exhausted. Either sleep a ton (me) or not well.
Without knowing it, your persona became enmeshed with your mom's. Who you are, versus you acting on behalf of your mom. They become entwined.
The slightest things will set you off. The grocery store is a big one.
First year milestones are rough. Birthdays. Holidays, honor days.
A flower. A sunset.
This helped me. I hope it helps someone else.