I finally got around to reading your thread here; it's great to hear that you and M are doing so much better now.
This site here (Polyamory.com) has surely got tons of info about jealousy, so use the "Search" feature and have a look around. But I also know of a few good external links you can use:
Let us discuss the greeneye monster shall we?
How to slay the greeneyed beastie.
The Theory of Jealousy Management
The Practice of Jealousy Management
Jealousy and the Poly Family
Brené Brown: The power of vulnerability
That last link isn't about jealousy per se, but it's such a wonderful presentation and has many applications, including jealousy, for sure. Well worth checking out.
May you and M share many happy (and challenging!) moments as the weeks, months, and years go by.