My mother-in-law told me about her husband's first love and ex-girlfriend. Should I tell her?

You shouldn't say it, because your mother-in-law just tells you your husband's past, so that you can know him better and make your marriage happier. If your mother-in-law really doesn't like you, why should she be so kind to you? And when you are pregnant, you should keep a cheerful and optimistic mood, which is good for your baby, yourself and everyone. If you tell your husband, he misunderstood her mother-in-law's kindness, and the consequences would be unimaginable. At that time, it will be bad for anyone.

I wish you and your mother-in-law harmony forever!