ETA: A highly recommended book for parents is "Back In Control: How to Get Your Children to Behave" by Gregory Bodenhamer. It's an older book but still available very reasonably on Amazon and other sites.
It's a quick read but gives excellent, very practical responses to common childhood problems of not listening, arguing, defying, etc. This would be very useful for you, to stick with specific, standard responses so that you don't get pulled into heated arguments where you lose your temper. Please check it out. I really think this could be of immediate help to you even before you start therapy.
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ORIGINAL:
I just read your other post, and from what you've written, it sounds like family and couples therapy is in order because these dysfunctional patterns have gone on for so long that you're feeling completely overwhelmed and stuck in this self-imposed helpless place where you don't know what to do.
That leads to just giving up and giving in, which leads to resentment, which fuels the rage. Which is exhausting. Which leaves you with no energy to do what you need to do.
You need some hands-on direction and guidance to get your parent-child and your spousal relationship back on a healthy path. Get a neutral third party to help you. You have four years left until she goes off to college or can move out on her own. Do you want these last years with her to be more of the same? Is that how you want your family's story to be written?
I think you know in your heart that you're not doing your daughter any favors by giving in to her and reinforcing her use of manipulation. Other people in her life, like boyfriends and eventual spouse, co-workers, bosses, friends won't tolerate this tactic. She needs to learn how to hear "no' sometimes and deal with it. We all do. Continuing on this current path is setting her up for failure in her current and adult relationships.
There is no shame in asking for help, so no excuses. Ask friends. Ask your primary care dr. or your ob/gyn for recommendations for a therapist.
When you go, don't give up because things don't change immediately (they won't). Also, give the therapist a chance. You're not selecting a best girlfriend here, but rather, you need someone who can be supportive while at the same time pushes you to do things differently, look at things differently. It's natural to be a little defensive, but don't let those feelings drive you away from therapy. It can work, if you stay with it.
For what it's worth, we are "older" parents, too. Our baby is 10, and my husband and I are 55 and 52, respectively. And honestly, my friends who are still in their early 40s and 30s report being just as tired as the rest of us. Your situation is less about age than it is about cultivating a healthy family dynamic.
Your words sound like you feel so helpless, but you are not. Make a commitment to your family by searching out a therapist today with the goal of having a scheduled appointment on the books by the end of the week. (To clarify: Not an appointment by the end week, but just have one scheduled).
Sending you thoughts of strength so you can get back on track!
J. F.