new perspective on an old hurt

so my kevin left to go dogsit for a week today. i was on my way to pick up cass from a birthday party (which was quite a drive because i can't take my car on the freeway) and i started to think about how much i felt like a part of me was missing because kevin was gone. and then it got me thinking about how i feel when cass goes away. when cass was smaller and wasn't with me, i REALLY felt like part of me was missing, but the older she gets, the less i feel like that.
in pondering this, i remembered an old painful memory. when i was maybe 13 or so, my mom met this "cool" guy named arne, i remember her coming to our house (my sibs and i lived with my dad) and announcing that she was engaged (to a guy she had known six weeks and we had never even met). and we were overjoyed for her - well at least i was - i can't speak for my sibs. when she took us to meet him i remember my little sis, who was probably 8, ran up to him and gave him a hug and said "hi new dad" and he stepped away and said to her "i don't DO dad". i was crushed for my sis and for us. it soon became apparent that arne didn't DO a lot of stuff (including get my mom even a token ring). it also became apparent that no DOing dad meant he didn't care much for any of us kids. so i decided if he wasn't going to DO a relationship with us, then i wasn't going to DO a relationship with him either.
at this point my mom had us two weekends a month and i told my mom that i wasn't going to come on her weekends if he was going to be there. and i remember her telling me "you won't be there forever. so if you are going to make me pick between you and arne, then i will pick arne" this killed me and our relationship was much damaged after that. i felt i had put up with a lot but her flat out telling me she would pick her new nasty boyfriend over me was a biggie. (he was a complete tool and she realized that after a few months as a side note).
to this day i think that is probably the most hurtful thing my mother has ever said to me (i have forgiven her by the way already). so, back to today in the car. i thought how different it feels when kevin goes and when cass goes. and i think i understand a bit more where my mom was coming from (not that i compare the situation exactly). i see that a mother can't build her life around a child forever. i mean, i am embarrassed to admit that cassidy's presence in my life has been the thing that has kept me going in the hardest times in my life. i feel bad that i have relied so heavily on her when i feel i should be the strong one. i know that many times it has been just her and i against he world. but i also know that part of loving her is allowing her to grow in the world. which means maybe being hurt, and most definitely being set free in the world.
i think my mother's comment to me all those years ago was coming more from fear, but i think i see a valid basis now. i think what my mom wasn't grasping is that just because your child isn't there to be your world when they grow, doesn't mean they abandon you. arne is LONG gone, yet my relationship with my mother has reached astounding depth that neither of us could imagine when i was 13. we are now simply beings, flawed in our own ways, who love each other and help each other in countless ways.
so back to the difference between cass leaving and kevin leaving. with kevin i have found the man with whom i want to share the day to day everythings of my life. and believe me - i know i have been rash with the falling in "love" my whole life. and that's how i know this is different. i am seriously making all the big, long-term decisions in my life according to what will best fit both my and kevin's dreams. so in one way i am bonding myself ever closer with kevin while detaching myself from cass. not in a love way, but in a plan for the future way. i am constructing my future with my and kevin's dreams, but cassidy's dreams are as of yet unformed.i am excited to find out what her dreams are and i will support her as best i can. but i realize that i cannot make decisions based on her dreams. and each time cass leaves it is a step toward our eventual relationship as true friends. i hope that we are close as my mother and i are when she is 32 and i am 54