Saying "your situation is, undoubtedly, more severe than mine" would mean that there is absolutely no doubt that your friend's situation is more sever than yours. The meaning of this adverb is pretty straightforward. It simply means without doubt or certainly. It's a very common, everyday word.

Saying "your situation is, undoubtedly, more severe than mine" would mean that there is absolutely no doubt that your friend's situation is more severe than yours. The meaning of this adverb is pretty straightforward. It simply means without doubt or certainly. It's a very common, everyday word.