Now, she says the wants to take it day by day and see how things go. Maybe try to regain our friendship and then maybe date eachother again.
Whenever you have opportunity, you need to let it show that you have taken back control and that she does not hold the reigns on your life. Why should it be left up to her how things need to go? Maybe you should decide whether or not you want to regain friendship with "her" or if you have a desire to date "her" again or not. See what I mean? As long as she feels that she is steering the wheel she won't give up much of anything, but the minute she thinks that "you" want freedom from her (and especially so you can see other women).....then her focus will be on what she has given up and she'll want it back. That is why I encourage you to act as if you think this S will be good. I really think you should approach her about dating others. See what kind of reaction you get and don't agree to any terms would telling her that you have to think about it.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!