but I don't seem to be able to stop it
Perhaps you are not ready to want to stop it ?
Which I think is normal.
When somebody still has strong feelings they are vulnerable to the "I pull\push you on elastic" game. But every time they undergo the "push\pull" the elastic weakens, and sooner or later it snaps.
You could just wait it out, or perhaps even hasten the cycle by putting some limits on his willingness to "pull".
Like saying for example "Fine OK, you say you want me to be with you, but you have mucked me about so much, this time I need a wedding date and a venue booked by you BEFORE we get back together before I can believe it is more than yet more words" (or some other significant condition you truly need to be part of the package to believe his "pull" is based on real, abiding desire to be with you, rather than a knee jerk reaction to you leaving).
It must be a condition that includes action by him to be completed before your return, not just words.
That works a bit like throwing a spanner into a perfectly oiled machine.
It is harder to be seduced by pretty words when you see somebody visibly baulk at putting them into solid action to support what is being spouted, cos they'd much rather limit themselves to just adding to the water vapour content of the air around them.
It is easier to resist being pulled back in when the pretty words dry up because they are being replaced with a million excuses as to why your condition cannot\should not be met.
What you might find is that you can't come up with a condition, because in your heart of hearts you know he'll never be able to satify it. Even that inner knowledge diminishes the power of his "pull" words, because they become that much harder to take seriously.