Focus on the positive reason that you’re doing the work, whether it’s for justice, or for a better future for yourself, someone else, or the whole planet, and discharge all the hatred and negative energy into the work, so that once you’re done you feel purged of it.
If you walked into a basement and your foe was tied securely to a chair, and you pummelled them into unconsciousness, or maybe beat them to death with a crowbar (that last being a visualisation I like to run before cursing, to see if that alone will purge my anger or resentment of someone, plus to test whether I am even that annoyed in the first place) then you wouldn’t expect to walk out from the unconscious or dead body still pissed, right? 
It would be done, the crunching, slapping, and wimpering would have done the trick - well, it’s that same feeling that you’re looking for.
I like to come out of this kind of work feeling like a holy avenging Daemon, not so much like a nasty little person throwing out spite-waves. 
If you don’t feel you have a positive reason that gives you that holy (unto yourself) feeling of anger and clarity, just work with protective wards for your loved ones, I’ll copy a link to a beginner-friendly walk-through for that below and also you can include “Harm none that I love” or suitable wording into both the opening and closing invocation of the spirits.
Walk-through on creating wards: