Father is right that Ordinatio Sacerdotalis contains "tenende" truth, not "credende" truth.
This means that one who rejects it, is according to canon law, "opposed to the doctrine of the Catholic Church."
That is not the same as the crime of the heresy, Father is right. But it does have canonical consequences, and moral ones, and spiritual ones, and at least potentially eternal ones.
Avery Dulles says it is not heretical to support ordination of women—& he knows a little more theology than you!