How should I manage my relationship with a sneaky academic?
Until you know a bit more, I'd start with a generous interpretation. Academics can be forgetful. They (we) can lose things like contact information. This interpretation may not be warranted, of course, but it is usually worth starting as if it is. It may be that what you were thinking of as fairly firm commitments, he was just musing about. It doesn't reflect well on him, of course, but your best way forward is to assume it is benign (for now).
Send him an email reminding him of past conversations and suggest that you are interested in collaboration. Send whatever support information you think useful. Go visit in person if that is feasible. Remind him of those conversations and your memory of them, but without being accusatory.
You will learn a lot from the response. In particular, you should learn if the generous interpretation is the valid one. I don't know that you have a lot of recourse, however, if he is a bad actor. But if not, you may be able to get the ball rolling on this or a similar project.
If he is a bad actor, you should probably have a conversation with your collaborators about how he treats them and try to figure out if you are treated differently. You and your collaborators can, perhaps, come to some understanding and even create a support group.

On Forgetfulness
One of my mentors, great person, great teacher, used to know when he was &quot;working hard enough&quot; when he would lose his car. You would find him wandering through the university parking lots looking for it when it was time to go home. Not a bad actor, but not always dependable.