Pesach vs. Pasta
As I've encountered more families finding ways to blend traditions, I'm always intrigued by the things that turn out to be sticking points. Your letter is a great reminder that even if a couple is not interfaith, their families might be, and the sticking point might not be between the couple, exactly, but may involve relatives, rituals and traditions that extend far beyond the choices they make for their own home.
If your husband wants to eat the pasta, I see no reason for you to try to talk him out of it. This is his family and his family tradition, and he's been walking this line his whole life. You might prefer he chose otherwise, but as long as his decision doesn't impact the kashrut of your kitchen or the food that you have to eat, it's really his choice to make.
As for your decision, if you don't want to eat pasta, then don't. Yes, leavened food is hard to resist, but if your practice doesn't include eating pasta, even delicious homemade pasta, then I would suggest that you not eat it. Your husband has always "taken a day off from Pesach" for this family celebration, but you haven't. I would imagine that you'll feel more consistent in your practice if you follow the Passover diet all week.
That being said, there's no reason not to attend the family Easter dinner. You can either choose to enjoy the non-leavened (and, presumably, non-ham) options at the meal, or you can bring your own Passover food and still eat at the table with everyone else. Yes, you may feel a little awkward. Yes, you may have to answer a lot of questions about why your husband is eating the pasta and you're not. Yes, you may salivate over the glorious Italian delicacies that you have to forgo. At least the extra saliva will help the matzh go down easier.
There are lots of ways to show respect, but you don't have to break Passover to do so. Hopefully, the respect is mutual and your husband's side of the family will respect your religious choices, just as you respect theirs. Maybe you can talk your way into another brunch invitation for some other occasion to enjoy the pasta. Maybe you just have to accept that this is one of the ways that Jewish observance impacts your life.
Whatever you decide, make sure that you and your husband are respectful of each other as individuals. If you decide, on your own, that you want to eat pasta out of respect for his family and not just because it's delicious, I won't tell you not to. However, I think the most comfortable balance you can strike is to be there in solidarity, and plan to bring enough matzah to share.