Freddie,
I haven't read all of the responses to your question so forgive me if this is repetitious.
As a Heart Patient, YOU don't need the additional stress of holding a grudge against your M I L, regardless of the justification.
In the Long Run, holding a Grudge against someone else is going to HURT YOU and damage YOUR HEALTH.
I hope you will find a way to reduce this stress on you, either through forgiveness or counseling.
I hope you will find a way to bring PEACE back into your Heart.
'AL Capshaw'