I agree with Sara...don't send this letter to MIL!
Best to just let it go....write and write and write and then burn, burn, burn. Write some more if you need to...burn some more. You don't want to re-read this stuff...it's rancid and toxic.
Think about what the reason is for sending it to her. Do you want to p1ss her off? undoubtedly that will work. Do you want MORE drama in your life? You'll get it if you send that.
detach my dear. Detach.
[Now where is that 'pot calling kettle black' icon]
