With this much on the line I would get a few second opinions from other lawyers. I would look at doing a 50% profit sharing of your current and future earnings

With this much on the line I would get a few second opinions from other lawyers. I would look at doing a 50% profit sharing of your current and future earnings from your company with her and 50% of profits from any sale in the future, she might make more in the long run but you aren't paying 50% of the current value over 8 years. Talk to more lawyers to make sure you get the best setup possible.