tantric practices with sexual intent are disclosed upfront, not to be a surprise to the vulnerable
Emma,
Generally speaking, ayurvedic massage is not supposed to be sexual in nature.
It is true that there are tantric techniques that are sexual in nature, and that ayurveda views a healthy sex life as one of the pillars of life but I seriously doubt that many Indian women would put up with what you are describing.
Tantra means "tool", not sex. Sadly the term is frequently misused in the West. Yes, there are sexual "tools", but they must be used appropriately and it should be clear up front that this is what is being practiced,and the intent is clear between both parties. This does not does not sound like the case you are describing. If your teacher's intent is to teach tantric tools or perform practices that are sexual in nature, it should be disclosed at the beginning and not be a surprise to you or any other woman.
You need to decide for yourself, but the fact that you are uncomfortable enough with the situation to post here about it speaks volumes.