K.V.
Where is your mother? Is she still in the picture? My husband had a poor relationship with his step mother for years. We got married and had kids and she didn't know where she stood in relation to the kids. They were her husbands grandkids, but she is not likely to get any blood ones of her own. My husband reached out to her and asked if they could call her Grandma? They don't know the difference,she is the only one they will know (on that side) and the relations between him, her, his dad, and all of us, became a 100% better over night. Really give some thought to the role that she plays in the family, would you want to go away for Christmas if you didn't feel accepted and loved? Then call her and talk about her role. Hopefully you will invite her into your children's lives and request that they be allowed to call her Grandma (children of divorced parents learn to love lots of grandparents) and she will be open and really show you the respect that you deserve as a member of her family.
I agree that if traveling really is a problem for her, and you know that it is about the traveling and nothing else, then you can go to them. I deal with this issue with my parents all the time. They don't travel, and I only live 2 hours away. It hurts my feelings that they don't come to see us, and sometimes it is important enough for me to travel to see them and when I am angry about it, then it isn't important enough and I let them miss out. I don't believe that it's just the kdis that are missing out. It really is my parents that are missing out, but it's their choice, not mine... or yours. Good luck!