They will study you to know what you wanted the most, and lure you back in with that. Sure, you'd been together for 5 years, but if you'd only know the real them, things would have been different, and you could have had a loving, passionate relationship and lasting marriage. The "real them" was just hiding for all five years, somehow.
They only want you back because you didn't stay down when they discarded you as planned, and there is still something left of you to wreck. It's not love. It is predatory.
You will know that you've become strong when they've hoovered, you've rejected them, and they give up and go look for an easier target of more vulnerable and insecure supply.