I wonder - when you meditate, are trying to control your mind instead of observing it?
Meditation is about (amongst many, MANY other things) understanding your own mind, the ability to detach from action/reaction thinking dictated by external things, and self-control, what it’s NOT about is sitting effortlessly in perfect lotus position, having a totally clear and one-pointed mindset, and not having any distracting thoughts or sudden bright ideas.
People who thibk they fail to meditate because thoughts come up relentlessly have never been taught this, which is why there is value in having proper teachers and guides IMO.
If you can observe your mind’s internal play and realise that it is fundamentally seperate from the You that observes it, then you will be one step closer to realising these negative ideas are just imaginary things, and that way you will not invest emotion in them.
Emotion is a fuel and also a kind of map for magickal endeavours, removing the emotion from the thoughts is therefore going to de-fang them in terms of their effects on your work.