My FMIL is a complete narcissist, but in the last few months she has gone into overdrive regarding our wedding. It first started when she found out my FI and I had received promotions, after which it seemed she expected us to pay for her to attend our wedding by constantly pleading poverty and guilt tripping (the poverty thing doesn’t add up at all for many reasons).
Since then she has told my FI we were rude and out of order for posting her wedding invitation and not hand delivering it, despite the fact that we posted every guests invitation including my parents. This then resulted in her saying she doesn't want to see my FI on Mother's Day, she's not coming to my FI's dress fitting, she's not coming to our hen do because it's not good enough as it's in my sister in law's house, when the only reason we are having it there is to save her money since she constantly complains about how much it's costing her to come to the wedding, and finally that she's not coming to the wedding.
When my FI told her she was being cruel she said that we have nothing to complain about as we have to expect people will complain about our wedding, noone is complaining other than her, and that her mum ruined her wedding day so we need to get over it.
She then sent about twenty messages trying to make us feel sorry for her and explain her behaviour which included random excuses such as "my heating bills are going up, I'm single and my dog died a year ago", said she will attend the wedding, but she's not coming to anything else.
This is where I need advice because she expects me to drive her to and from the airport and spend the week she's in Italy, where the wedding is, with her, and I just know she's going to be playing mother of the year in front of everyone else and it's eating me up inside that I'm going to have to go along with this because it's our wedding and she's extremely volatile, so anything she perceives as a criticism will make her explode.
I want to tell her how much she's upset and offended me because I can't stand the thought of playing happy families with her after all the stunts she's pulled. My FI is happy for me to talk to her about how I feel and get things off my chest, I'm under no illusions that she will change her behaviour by any means, this is more for me really, but is this an awful idea?