Regarding Mass Attendance Today, most of the "Traditional Latin Masses" are offered by invalid priests, & the valid Traditional Latin Masses are held by heretical groups (SSPX, SSPX-MC, SSPV, CMRI, …More
Regarding Mass Attendance

Today, most of the "Traditional Latin Masses" are offered by invalid priests, & the valid Traditional Latin Masses are held by heretical groups (SSPX, SSPX-MC, SSPV, CMRI, FSSP, etc.) who believe that people can be saved in false religions. These groups also impose their heresy on true Catholics who profess the truth that the Catholic faith & baptism are necessary for salvation (Matthew 18:17 & John 3:5).

The obligation to attend Sunday Mass currently does not apply, because there is not a fully Catholic option available for most today. On Sundays, people should stay home & pray the 15-decades of The Rosary. One could also have a spiritual communion (in a state of grace) & practice devotions like the Way of the Cross, etc.

If you go for confession to a priest & he asks why you don't attend Mass, I would charitably tell him that you are not entirely sure what he believes. To attend a Mass, he must answer the following questions:

1) Do you believe that non-Catholics need to convert in order to be saved?
(if he says "no" or the same thing in an ambiguous way, then do not attend his Mass)

2) Do you believe that it is acceptable to pray with non-Catholics?
(if he says "yes", then do not attend his Mass)

3) Do you believe that John Paul II was a saint?
(if he says "yes", then do not attend his Mass)

If he responds to these questions heretically & continues on why you're not attending, you can mention charitably that you will not attend because what he believes in unfortunately inconsistent with Catholic teaching. Most heretical valid priests under the Vatican II sect (Eastern Rite or pre-1968 Roman Rite) won't take much issue with those firm in the correct positions to the point where they refuse the sacraments, but the false traditionalist priests (SSPX, etc.) oftentimes will refuse sacraments after crucial questions about the faith, which is why such groups are notoriously heretical & no sacraments should be received from them.
Where To Receive Sacraments