Zid that is crystal clear.
looloo - there is a lot of painful history leading up to this which must be very frustrating for you especially as your MIL is trying to re-write this history.
I would respectfully ask what you want to achieve from this situation? What is your desired realistic outcome and what can you do to achieve this?
If you want you MIL to say sorry and change how she treats you then that may only be achieved through contacting her, getting her agreement to go through some of the issues. This would take a not inconsiderable shift from her current position, take some time and eventually rely on her changing - is that realistic?
If you want her to make some positive contribution to your child then some of the above may still be required or you yourself will be fuming mad any time you see her.
It seems so unfair to let her off the hook for a) being dishonest about the situation and b) not even caring about her own grandchild, although if you are better off without her influence - should you simply keep her out of your life?
Hope you manage to let off some steam.
mmxiv