Getting married in a few days time. DF and I have been together for 3 years. Started long distance, I moved 12 months ago to be with him. Not sure I identified at the time but think I did carry a lot of resentment towards him for missing my family and friends/feeling a bit lonely etc - but a year on, lots of nice friends and get on with all of his family really well, with the exception of, up until 2-3 months ago, his fucking psycho, nuttier-than-nuts, deluded, narcissistic, bitch of a mother 
She has interfered in every relationship he's had, played an integral role of splitting them up and has very aggressively tried the same with me under the guise of a lovely caring lady who bakes/knits etc. It's very clear that her "polite" efforts of getting me to leave didn't work and with a few months until our wedding, resorted to genuinely delusional behaviour.
SIL and BIL are both NC with her for the exact same reasons as I dislike her, we've discussed her awful behaviour many times and I am confident that I have tried my hardest time and time again to be kind to her knowing full well she will make nasty comments about me to whoever will listen, continue to push boundaries and cause upset. I am NC with her, DF has very limited contact.
She "claims" to have varying ailments which she is seemingly immensely proud of. I have a background in medicine and genuinely find some of her claims completely implausible. I'm pretty sure most are either exaggerated or invented.
In January she had a standard mammogram which showed a cluster of pre-cancerous cells which required a very simple operation to remove - I know this as she gleefully waved the full report from the consultant in my face.
"I have the most aggressive cancer that my consultant has ever seen in [insert county]."
I explained my explanation of the report to her in the most tactful way possible and the next day read with interest her Facebook post about her very aggressive cancer 
Alongside 99% of the UK, I've lost loved ones through this disease and find her lies lowest of the low, pure attention-seeking behaviour. This is just one example of the lengths she will go to be deceitful and ensure the world rallies around her.... and with the exception of FIL, no one actually does, what a surprise 
DF is the most supportive, empathetic and understanding human you could possibly meet. He is kind, generous and so very thoughtful (hence why I'm marrying him in a few days time ). Over the past 3 years, we have had such a lovely, happy relationship and have only ever had big rows since his mum came in to stir the pot.....
HOWEVER, due to various reasons, the number 1 being that we both love FIL to bits and he will not come alone, her invite to the wedding has not been rescinded. SIL and BIL are on standby to remove her should any nastiness occur.
Yet I still feel miserable at the situation 
I completely kicked off at DF last night because I'm pre-empting her ruining the wedding. He has tried to reassure me that no matter what happens, we will still have a lovely day but feels frustrated that he can't do anything to make me feel better. I am so resentful that in the lead up to the wedding, I have nothing but panic wondering what she is going to do to ruin it - I'm genuinely not even excited but absolutely feel sick.
Is this normal, pre-wedding nerves??? Mind has been racing all day, I feel sick thinking about it. AIBU letting my stomach tie itself in knots about this or do I seriously need to grow up.....