My husband always speaks for his mother. I sent him a long message. When he came back, he talked and laughed as if nothing had happened.

That's what men do. What you think is important is not important at all in his eyes. So, when you are upset about this matter, he can talk and laugh freely with others.

You sent him spit. Did he speak for his mother? In that case, you don't need to worry that he will be angry at all. Because it's different when you tell him what the fuck isn't. Although you are married to him, emotionally, the mother who has raised him for decades is definitely taller than you, so once you complain about his mother, he will feel uncomfortable and angry. But you are complaining about what he said, and this becomes a matter between husband and wife. Many men don't take such complaints to heart. A good man understands and comforts his wife.

In this family, you and your mother-in-law are definitely higher in your husband's mind than your mother-in-law, so once you have a conflict with your mother-in-law, he will favor his mother and speak for her.

If the problem of mother-in-law and daughter-in-law becomes a problem of husband and wife, your husband's endurance will become greater, so what seems bad to you is just a wife's ordinary complaint in his eyes.