MB,
I feel I can speak to this as our children were born abroad where we lived until the oldest was 8 and we had different experiences. Our oldest refused to speak the native language to us, she said, "you are Mommy, you speak English" even if our guests spoke only the native language and she went to a local school and spoke the native language. The second child refused to speak English as she wanted to be like her friends and was more involved in the local community. The 3rd spoke only the native language and my mother had to teach him English when we would come to visit and then we had to reteach him native language when we went back. That is all background.
I work with an immigrant population here. This is my experience. All kids will learn English. All kids will have their immigrant language erased unless the parents work really, really hard to maintain it and the culture. There is so much to be said for being bilingual. It opens so many doors. My daughter is taking classes to be certified to teach ESL and she learned that every immigrant group has their language erased by the 3rd generation. Your grandchild will not know your language. So, my advice is to maintain your language and culture. I know it is hard. There must be local kids' groups which study art, dance, celebrations etc which help your daughter to identify with her culture. We are a melting pot, but it is good to have a few flavors stand out and I would support it fully. My own background is 4th generation born in the US of 100% Irish forebears and we were still talking about the glories of being Irish when I was a kid. So.....I disagree with your husband and I hope he can see that to erase a learning opportunity for your daughter will do her no favors. If school speaks English and home speaks X, she will not be confused. I would not comment on her speaking English, just respond in your native language so that she hears only that from you.
I think pre-school is a great idea so that she won't need to learn English and the subject matter at the same time in first grade. Many kids go into the straight English program from the pre K and K bilingual programs.
K. C