Advice on ridiculously busy friend ??

Hi there,

I'm new to this board. I'm 53 years old, 2 kids, 4 step kids (all 23 plus), stable relationship and work full time. A problem I am struggling with is that my oldest and dearest friend (who I have known since I was six !) is so chronically busy and is always in a rush or stressed out. Since we both had babies, she gets up at 5:30 am and is busy until 10 pm when she has a bath and goes to bed. She is still doing it even though all her children have finished school and two of them aren't even at home !! She resents her husband because he goes off on bike rides and short trips and she is always committing herself to hosting large family dinners etc. We used to meet for lunch in the city where we both work, but last time she cancelled on me and the time before that she forgot. When we do meet she is so stressed out about how hard it was for her to make it that I feel guilty and don't enjoy meeting like we used to. We also meet regularly for dinner in a group of six and always have to book 6-7 weeks ahead because she is over-committed by which time all the news we share is old. The next one is in a months time and I invited everyone to our beach house for the weekend, for a change. Everyone else could come but she just brushed it off as impossible, even though she really has nothing she HAS to do that weekend. I was really hurt, because I wanted her to seriously consider it as an option that she might enjoy. What should I do ?? I;ve told her my feelings but she got defensive and started off on another round of how busy she is.