Hello, for how long have you been teaching Spanish? My case is different. I come from a Spanish speaking family, but since I was raised in US my whole life I dealed with the same issues as the average American, except that my accent was slightly different and spanglish appeared oftenly. It was corrected with time and in college with an intense study of the language.
Anyway, I can tell you CPI is a good choice, they have a Spanish program for teachers, taugh by native speakers with a lot of experience in the field. At first, I went to CPI for the adventure tours haha, but I’m glad I took the course since it helped me to understand advanced phrases and alternative terminology which can only be learned from the source.
Hope it helps!