I think it is entirely appropriate to feel sad. If we 'lose' anyone close to us it is hard around birthdays. This can include parents, and children, and we have effectively lost our spouses, as surely as if they had died. They have gone out of our lives, without kindness and consideration that could leave sweeter memories.
If you were sad every day, well then you might need some help, but on your birthday? Honour the sadness, and the great love you felt, that is at the root of your feeling sad.
I sometimes think we spend a lot of time here, probably rightly, encouraging people to come out of their grief. But we should not, imho, deny that there is a grief, and that we will feel it at key times, for quite a while.
You are not wallowing in grief, you are experiencing it.
And no matter how accomplished you are, the failure of a marriage is a BIG thing for any person who thinks and feels.
So I am truly sorry for how you feel, but hope you will not beat yourself up about it. Maybe it is the day for quiet mourning, until you no longer need to. So instead of beating yourself up for how you feel, go with the feelings. Just a thought.
