“Do I offend God if I stop going to the New Mass?” Answer: No.

Thanks for the e-mail.  No, you definitely cannot go since the removal of “many” from the consecration is not the only problem.  The removal of “mysterium fidei” (the mystery of faith) also causes a doubt about the validity. 

Pope St. Pius V, De Defectibus, chapter 5, Part 1: "The words of Consecration, which are the FORM of this Sacrament, are these: FOR THIS IS MY BODY. And: FOR THIS IS THE CHALICE OF MY BLOOD, OF THE NEW AND ETERNAL TESTAMENT: THE MYSTERY OF FAITH, WHICH SHALL BE SHED FOR YOU AND FOR MANY UNTO THE REMISSION OF SINS. Now if one were to remove, or change anything in the FORM of the consecration of the Body and Blood, and in that very change of words the [new] wording would fail to mean the same thing, he would not consecrate the sacrament." Pope Innocent III, Cum Marthae circa, Nov. 29, 1202, in response to a question about the form of the Eucharist and the inclusion of "mysterium fidei" (found in Denz. 414-415): "You have asked (indeed) who has added to the form of words which Christ Himself expressed when He changed the bread and wine into the Body and Blood, that in the Canon of the Mass which the general Church uses, which none of the Evangelists is read to have expressed... In the Canon of the Mass that expression, "mysterium fidei," is found interposed among His words... Surely we find many such things omitted from the words as well as from the deeds of the Lord by the Evangelists, which the Apostles are read to have supplied by word or to have expressed by deed... Therefore, we believe that the form of words, as they are found in the Canon, the Apostles received from Christ, and their successors from them."

Second, the Polish priest is probably ordained in the new rite of ordination; if so, he’s not even a priest.  Third, supposing for a second that the Polish priest is validly ordained and celebrating a New Mass that is valid because it includes the entire form, you still couldn't attend because the New Mass is a non-Catholic service.  Regarding your concern about offending God, you would be offending God if you go to the New Mass.  People need to remember that the third commandment is to keep holy the Sabbath, and it’s the Church’s law to hear Mass on Sundays and holy days; but this Church law only obliges you if the Church provides you with a fully Catholic church in your area.