Hi yesterdaysmom,
From what I can gather, it is not possible to tell which nerve a schwannoma is growing on. If you look at the MRI report, it will say something like "consistent with a vestibular schwannoma". They normally say it's growing on the vestibulocochlear nerve (Cranial nerve VIII) since that is where 95% of them grow. People have gone in for vestibular schwannoma surgery only to have it altered or aborted since it is growing on the facial nerve (Cranial Nerve VII).
The good thing is that schwannomas are slow growing, non-malignant and I have not heard of any case where someone has died from their schwannoma. (About .5% die, usually if infirm, from surgery and an unknown number from doing nothing.) The main thing is that these tumors are slow growing and you have plenty of time to evaluate options (surgery, radiosurgery or observation).
Did they mention how large your tumor is as that affects urgency? Also, how long have you had symptoms?
From what I gather, you have already been diagnosed with a schwannoma, it's just a matter of finding out more. This may result in the ENT not rushing to get back to you. (If it was a new diagnosis, they would have gotten back to you straight away, if my case is common.)
Your cousin's husband who died from a brain tumor probably had something far more serious such as a glioblastoma, which is malignant brain tumor.