A
Aeden
Guest
There’s a lot of books you can use, it really depends on your learning style. Try starting out with a book series like Wheelock, it gives you very good explanations of all the grammatical nuances. Using it with Henle, which provides a metric ton of exercises worked well for me. Since you’re learning for the mass and prayer, which tends towards prose structure of Latin, that should be good. Fair warning though, it is not a language for the soft-hearted. Best of luck!