Welcome back to the Wefugees Community and thank you for reaching out to us again.
I am not familiar with the (new/post-Brexit) UK related residence regulations in Germany. If you got married after the issuing of the residence permit, your husband's residence permit might be connected to the children, I assume? However, I don't think that it is not possible to obtain the residence permit as spouse instead of father of a UK citizen (if your children live outside Germany). In that case, you need to talk to the immigration office. Of course it will be important that your marriage is officially registered and recognized here. It might be also interesting to check what exactly is written on the residence documents.
I will link my dear colleagues @mbeon-Gabriele and @mbeon-Christine here as well. Maybe they are more experienced in this field and can add some information.
In any case, please also don't hesitate to get back to us with any further questions.
All the best,