having been in a similar situation, my divorce was finalized a little over a year ago, but we were separated for the previous 2 years, I know of what you speak.

The blunt answer is yes you are cheating!

Logic and common sense may dictate that you aren't, as you are separated, but by legal definition until your divorce from your wife IS FINAL, any activity you have with another woman still constitutes cheating, and yes you are comitting adultery.

Keep that last sentence in mind, when it comes to how you handle your relationship with your new woman, because if your not-yet "ex wife", and her lawyer find out about your newest woman, be aware they can and likely will drop the hammer on you for your adultery.