When you are baptized, even by heretics, you are baptized into the one true Church!
You have to be more specific than that. If you are baptized by heretics and believe as they do, you are certainly NOT in the one true Church of the one true God.
If you are baptized by them because of necessity and you hold the Catholic Faith, then obviously you are Catholic.
If you are baptized by them and are an infant, then you are a Catholic until such a time as you have reached sufficient age of reason to be accountable to the Divine Law and still recognize their sect as the correct one, or at the very least have not yet professed the Catholic Faith and subjection to the Roman Pontiff.