What helped me keep a cordial and respectful relationship with my kids' dad, was what I refer to as "The Cousin Paradigm".
Imagine a cousin that you've known for a long time, part of your family, you care about this cousin and want the best for him. That being said, you're not enmeshed in his life, he can come and go, and that's okay.
So, your STBX is now the main variable in "The Cousin Paradigm". I don't know if this helps you, but it really helped me to be able to "name" the new stage of our relationship.
Also, his renewed interest in you is pure WAS "script". It will get more intense so buckle up.
