I still want to make this work

[gr8 day 2B alive]

Basically, I want some advice on how to communicate to her the amount she owes me, and to reinforce the fact that she needs to stop using our joint account since her checks are no longer going there. While being 'dark' is it OK to call/text to let her know? Should I wait? Any advice on how to word it?

You should not have a shared account with her if her check is not going into the account.
You need to close the account and open a new one in your name only. That way when you pay bills the are soely paid by you and not a Joint account. Paying from the join account means she actually paying half the bill even though you're paying for the whole thing.

You need to protect yourself financially too.
I opened a new account to start paying for the Mortgage.
Do not have any joint accounts or credit cards.