Hello Tobi (Tobias?),
I see what you mean. Dosa can be overcome with metta. One can be trapped in dosa mindset. When you understand more and deeper dhamma concepts you gain knowledge and dosa will not appear that much. Even the effects of metta bhavana will be enhanced. So both work in the same right direction.
As add-on relief try to forgive those bad persons and ask for forgiveness from your side. That will also calm your mind. At the beginning it may not be easy but the more you try the better it will get.
By the way, the aim of real Buddhist meditation is to contemplate Dhamma concepts and to compare one’s own experience for validity. This creates real understanding and trust in the teaching. With understanding the defilements will vanish.
Tobias / Heiligenstadt