I dont know you her or the situation, I'm not a pro, I dont give advice, and I screw up every part of my own life everytime. But I share what I've learned in 41 years.
And 16 years is a long time, 5 times longer then my sham marriage.
But 45 leaves you about another 45 to go, lots of time to TRY to have some happiness. The question to ask yourself is what you really want. If you could stay with her and be happy together? Or are you completely sure your want nothing more to do with the whole thing and would just be happier being done.
If you want to work it out I'm sorry all I can suggest at best is the usual cliche stuff. Treat her like you just started dating, candle light dinners, flowers, romantic getaways, stuff you had fun doing when you had fun together. Sometimes that stuff works.
If your done and know it for sure, get a good lawyer, be out of your way super nice to her the whole time in every way. Divorces always get a little nasty, you will say and do stuff you will regret and hate yourself for.
And if you do start the divorce there is NO going back. And believe or not you will miss her and want her back at least a little, no matter how else you feel about.
But whatever you do dont spend the many more years you still have in life being stuck and miserable.