You could actually have a conversation with your wife and her family. is that not worth it to learn? Why would you even marry someone if you cannot communicate?
I like to understand what people say about me not realizing I can understand most of what they are saying. I have been called a dirty Indian and even told no Indians allowed at a bar even though I am not Indian or Middle eastern at all. It's like no one has heard of Mexicans in Thailand. I guess we look close enough to Thai people that they think I am Indian.
I had a huge issue learning it and then I hired a private tutor for the next 6 months. Made a world of difference especially since conversation Thai is a bit different the school Thai. It was tough but I am so much better now.