My mother and my husband-to-be can't get along

I'm currently 11 weeks pregnant and is supposed to be happily preparing for my small wedding to get married this year with my husband-to-be. My husband-to-be and I discussed previously that we wanted a baby so whether it's before or after marriage, we're ok. My mother isn't happy when I spoke to her about how I'm now pregnant before marriage because she's someone who has very traditional mindset. She thinks that "we did something wrong" and that "we did not plan our pregnancy properly to be after marriage". I can understand why she's angry, but honestly, we don't think we did anything wrong by wanting a baby and me wanting to be pregnant. When my husband-to-be came over to speak to my mother about the marriage details, her attitude towards him was very bad and rude - she refused to look at him when speaking and was confronting him like a "criminal" until he mentioned that "we will be doing guo da li + a banquet" to appease her. She demanded for a lot of things which I don't think was necessary and I was appalled because before this visit, I actually told her I wanted a simple ROM only and no banquet, and she told me she was ok with it since it's now covid period and that it's "troublesome". I didn't speak up during this conversation to confront her because I know how defensive she will get and how it will make the whole conversation turn ugly - I admit this is my fault for not speaking up for my husband-to-be at that point of time. A day before the second visit, I told her in private that I really don't like all these traditional stuff and I just wanted a simple ROM, that's it. She got pissed off and we ended up in an argument - with her saying that she's "not asking for a lot already" and that I am "worried that my husband-to-be will have to spend a lot of money on the wedding". In my opinion - he paid for the downpayment of oue future house alone, I didn't fork out any money for it; he is taking care of me and takes time off to accompany me to gynae checks; he has a car loan to pay off; he has his own retired parents to take care of; and now we are having a baby on the way. And she's expecting him to fork out all the money himself for the wedding as well. The whole conversation didn't end off well in the end. The next day, my husband-to-be came over to visit and discuss on the wedding plans again. Again, my mother, with a black face, refused to look at him for the first 15mins until he said "Ok auntie, we will still do the GDL and banquet". I can tell that my husband-to-be was already unhappy but he was still sitting there patiently, trying to appease her. Again, I didn't speak up because I had an argument with her the day before and I knew things will turn ugly if I intervened that day - this was definitely a mistake that I made. After all these, my husband-to-be told me that he don't feel welcomed to the family at all, and asked me why I didn't stood up for him at all during the conversations. I told him I did, but I did it in separate occasions and it didn't end off well. He wishes to have an apology from my mother for being rude before we proceed with anything else. On the other hand, I don't trust that my mother will apologise willingly because she don't think that she's rude at all. I know he doesn't deserve all these treatments from my mother, but I feel really helpless now as to what I can do to make him feel better. I've been crying daily whenever I think of these issues and I feel really helpless because I'm in the middle. #advicepls #pleasehelp