Abemacivlib/Verzenious - I'll be taking this alongside Letrozole. So worried about the side effects. Can anyone share their experience and ease my fears?

Hi there.I am due to start taking this drug alongside Letrozole next week for 2 years 

I am ready worried as I could not complete my chemo infusion as it made me so unwell.

The side effects from this are the same as I had before I am so worried I am going to be so unwell again and loose my hair again which has just started to grow back.

I keep thinking surely I can't take something that makes me unwell for that length of time!

I know they can reduce the dosage but it is really worrying me.Can anyone out there share their experience and hopefully ease my fears 

Thank you so much