Hello @rosez, I'm glad to hear that your husband is seeing a speech therapist, that is a good start! I suppose that his/her idea to correct your husband when he makes a mistake in his speech is his/her opinion but might not be the right approach for your husband at this time, especially if he seems frustrated at your attempts to do so.
Has the speech therapist suggested reading out loud? This can be a gentle way to get a speech problem corrected. If your husband likes to read something in particular, whether it is magazines, newspapers, or books, you could both read out loud together, taking turns (perhaps a paragraph at a time) and see if this helps him to have better speech. Has your husband had surgery or other treatment for this brain tumor? If so, how long ago was that?
@verilee1776, Thanks for sharing your thoughts and experiences. You are right, each individual situation is so different and everyone must find their own way.
Here is a video with suggestions that you might find helpful,
His therapist did tell me to speak slowly and in short sentences. He isn't a music person but does like listening to Pandora on long driving trips.