Then divorce her... Get your ducks in line. (All of them) Then worry about poly.
You have unfinished businesses that needs to be taken care of and it its NOT FAIR to pull someone into a potential shit storm.
40 yo straight female
Married in the eyes of the government to Butch since 2001...
Murf my monogamous second husband has been with me since May of 2012.
In a V relationship with an average 60/40 split of time. Only due to Murf's and Butch's crappy work schedules.