So long as you realize that you’re kicking both your roommate and his girlfriend to the curb, then go right ahead, knock yourself out.
That kind of money brings out nastiness in everybody. You don’t want that in your life. It’s going to come from her boyfriend just as it’s going to come from her.
Dump them both. If you can’t get along with them now, you’ll definitely not be able to after she’s got a cool $500k in her pocket.