Given that the woman had already been baptized in the Catholic Church, there was no need for her to "bless" her baptism in any sense. Deliberately participating in the rites of another ecclesial community likely constitutes what canon 1365 of the Code of Canon Law calls "prohibited participation in sacred rites". According to the canon, this is to be punished with "a just penalty".
What constitutes a just penalty, then, and how is it imposed, and who has the authority to impose it? First of all, a "just penalty" is one that matches the severity of the crime—so it would have to be determined by the judge (i.e. the one imposing the penalty) that it is a reasonable response to the crime; neither too harsh nor too lax. Forbidding someone from receiving communion is rather harsh, but has been imposed by some bishops (for example, on politicians who vote in favor of bills supporting freer availability of abortion).
This brings us to the last question: Who has the authority to impose such a penalty? It is, in fact, only the ordinary who has authority to do this. It is certainly possible that the ordinary has issued a letter to each parish stating that exclusion from Communion is the standard response for deliberately participating in the sacred rites of another ecclesial community. Absent such a general rule, though, the priest has no authority to do this on his own.
If the bishop did not impose such a general penalty for the diocese, then (given that the priest had no authority to impose it in her case specifically) is the woman excluded from Communion? ABSOLUTELY AND CERTAINLY NOT. Canon law is very clear about this. If the woman is not under any sort of censure or penalty, she must be allowed Communion at a reasonable time.
Sacred ministers cannot deny the sacraments to those who seek them at appropriate times, are properly disposed, and are not prohibited by law from receiving them.
Canon 843, Section 1
As far as telling her this in front of the whole congregation: There's nothing in Church law prohibiting the priest from doing this, but it certainly seems out of keeping with his pastoral responsibilities. Even the ordinary, apparently, is obliged to warn the person before imposing a penalty (Canon 1347 section 1).
- It is not clear whether the bishop had created a general penalty of this sort. This can be discovered by inquiring at the chancery (the administrative office of the diocese).
- If he had not, the priest had no authority to forbid the woman to receive Communion, and she is not in fact forbidden. One ought to report the priest's action to the bishop or his representative.
- The priest was tactless in his treatment of the woman, regardless; if there is a concern over this it should be taken to the pastor of the parish (if the priest is not the pastor) or to the bishop.
- She did, however, commit wrongdoing, and should go to confession. Whether this is with the priest involved or not makes no difference.