I have been a practicing Witch for quite a while now. Like a really long while. I do not claim to be perfect, or to know everything. And I have made mistakes in the past. Part of being a Witch, of working with Magic, is owning everything you do. You have to own your Magic.
Magical ownership is important. It means that you will take responsibility for whatever the outcome, for better or worse. That is incredibly easy when things go just right. You smile and point and say, "Yea, I did that. That is my handy work." Or when you do a Magical working to heal someone and they become healthy and whole. You smile and point and say, "Yea, I did that. I healed that person." When everything works out right, when nice, shiny, positive things happen, it is easy to take ownership.
It is much harder when you make a mistake. You send out healing energy to someone who is really terminal and needs release; so they linger on the border of life and death a little longer than they should. You do a spell to get a promotion at work, and you get it, only to find out that you took it out of the hands of someone who was in desperate financial need of the promotion and the raise in pay. You cast a love spell (don't do that) on a guy you see at the gym because he is really hot and really sweet, and he becomes obsessed with you, leaves his wife and children, and becomes a scary, creepy stalker.
All of these things are your handy work, whether or not you choose to claim them. Owning your Magical mistakes is the first step in fixing them. By saying, "I did this. I made a mistake," you put the energy out there that says you are owning it. The universe will then be far more accepting of helping you fix it. Every Witch will make a mistake or 20 in their life time. It happens. Owning those mistakes is the start of the road of learning from them, and, hopefully, fixing them.
The collateral damage of Hexes and Curses can, sometimes, not be fixed. Not all Witches work with this kind of magic, because they do not wish to live with whatever consequence that may arise from them. There is nothing wrong with that as magic is always a matter of choice. Those who do, often do so with the understanding that they must take ownership of their Hex or Curse, and whatever may come from it. They should never be taken lightly, and really require serious thought before executing. Your target does not live in a bubble, and there is a real possibility that someone around them could potentially be effected by your Hex or Curse. You have to accept ownership of that. Your Hex or Curse could also result in something very detrimental happening to your target. You have to take ownership of that as well.
Magic requires ownership, requires full awareness of the consequence and acceptance of these consequences, even the unintentional ones. A Witch who owns their magic, who really gives serious forethought to their spell work, who does not just fling spells out there without care, is a Witch who is truly worthy of being called a Witch. All others, really aren't. If you are going to use Magic, own it. If you do not, then do not call yourself a Witch. You are an accident waiting to happen, and eventually the universe will teach you a lesson. Witchcraft is not about doing whatever you want, but rather acting with the understanding that you are responsible for your actions. And, taking ownership of your own magic.