I'm a little late in responding to this, but I just wanted to let you know you are not alone. I have dealt with this since my kids were born. I have two really terrific kids (I say this because they are really delightful to be around, and I wouldn't necessarily blame people not wanting to be close if they were bratty!) My two are the only children on my husband's side of the family, so you would think that they would be considered special.
We get together on the obligatory holidays or when something special is happening with them. A few years ago they were traveling back (right through our city) from a summer vacation spot on my son's birthday and couldn't stop by our house.
I have been the one to say the same thing as your husband. "don't expect, and you won't be disappointed." But it's hard not to be That isn't what family is about for me. But that's the difference. I have different expectation about what I want for my kids and what family is. There's not a lot that I can do to change how they are. And I have learned that their dysfunction is theirs, and it has little to do with me or my kids.
After a while you do learn to expect less and it doesn't hurt as much. We still let them know what's going on with our plans, but we put the most importance on what's best for us. For instance we used to plan our summer vacation around the "family" vacation spot they always use and try to coordinate it with them. We ended up doing all of the cooking, not having proper accommodations because they would choose the rental house, and I ended up with my kids because they would all go off and do their own thing together. Now we plan our our vacation and if we're able to go up for a day to see them we do, if not, we don't.
Good luck Mama. I know it' hurtful, but they are the ones who are missing out. Surround yourself with family and friends who want to be involved and close to you and your kids and try to let go what you can't change or control.