Can someone tell me how much damage (if any) I did with the emotional breakdown I had with my 8 year old daughter?

I've posted a few times on here about my daughter being one of those kids where "nothing works" no matter what we try, whether it was reward charts, sticker charts, other reward stuff, light consequences, severe consequences, whatever. We also have a 3 year old who is acting like a typical 3 year old, but is also taking cues from the older one and copying a ton of her bad behaviour which really pisses me off.There have been many, many times where I have had to leave the house and go and sit in the car or garage, or wherever and just have a good cry. I have also seriously regretted having kids numerous times over the last three years. This comes and goes and I usually have about 1 - 2 bad days per month. I don't openly show my "dislike" for my kids when I'm going through these episodes. They always seek me out and we play together a LOT, they cuddle with me on the couch, they get excited and run and greet me when I get home and all that other stuff. I know they love me and I'm pretty sure they know I love them but hooo boy are there times I just want to run and not look back. Things have gotten better recently but over the last week things kind of reverted back to shit again with her being defiant, belligerent, rude, and just generally shitty. On top of that, I am already a little stressed out with things that don't have anything to do with her.The way things just seem to have worked out is that I take her to bed and my wife takes the little one, and this is where I don't know if I fucked up or not. I tried to have a heart-to-heart with her before reading time, where my plan was to try and give her a little pep-talk about how much better things were getting and how I appreciated her trying to be better, but for various reasons (including a particularly tough day with her) I couldn't keep my shit together and I lost it. I had a complete emotional breakdown in front of her. I was crying, sobbing, shaking, etc., and in between the sobs and tears I managed to get this out:"I just hope that when you get older that realize that your mom and I aren't trying to be mean to you and make you unhappy, and that all we want for you is to be happy, healthy, and safe. We are trying our best and I'm sorry that that isn't good enough for you. You just seem so mad at us all the time and we don't know what else to do to make you happy. We really are trying to be the best mom and dad we can be"She said "awww" and gave me a hug, and then we both just laid there in awkward silence while I tried to stifle the tears and sobbing for a few minutes before I kissed her, told her I loved her and left.I have often read here, and in /r/relationships as well as other, more legitimate places that saddling your kids with your emotional issues is a big no-no, but this is the first and only time it's ever happened, and this "emotional issue" was directly related to her, so I'm not really able to see this clearly. Did I fuck up, did I send a strong message, or will she just think I'm some kind of loser who can't even be a dad to a 7 and 3 year old? via /r/Parenting http://ift.tt/2hNT8Ya