Maybe passive-aggressive is the wrong term for it, but it doesn't matter what you call it, it really isn't conducive to the relationship. I'm willing to bet that your plan will not bring you closer to your goal. She acts in a certain way, in this case continues to call and trying to be friends. You don't want her to just be friends with you. You want more. When she doesn't provide you with more, you get upset and come up with a sarcastic way of handling it, ala "I judge from your actions that you want to be more than friends" when she had no such intentions.
She isn't going to kick OM to the curb or try again with you just because that's your desire. She isn't going to try again with you just because if she doesn't you won't talk to her anymore. She is only going to do that when she makes the choice to. In the meantime, what are you going to do, regardless of her? What is it that you plan to do with this relationship as it stands now (and may always stand...just two people with 20+ years of history together that talk on the phone)?
I think you need to really think about whether what you really want is to never hear from her again. Is that what you would prefer over the contact you have now? If you truly can't be friends then I suggest being more direct, like, "this is really hard for me, after all our years together, to just talk as friends while you are with another man. I would really appreciate it if you would just confine yourself to talking to the kids. Calling me is sending mixed messages that I'd prefer not receiving."
In the end, it's not the years in your life that count. It's the life in your years. Abraham Lincoln
It is hard to fail, but it is worse never to have tried to succeed. Theodore Roosevelt
