In which episodes where that woman that was pregnant and had a brain tumor and when she died Derek went dark?

I think it's in the two episodes: An honest mistake and I will follow Du into the dark. 5x16+17

True, In 'An honest mistake' the woman actually dies and in 'I will follow Du into the dark' Derek goes all dark with him sitting on the couch all Tag and being drunk in his trailer.

but she was also in two episodes before it...she came in 5x14 - Beat your herz out then she still was there in Before And After and dies in An Honest Mistake...