Colloquially, this term is usually constructed with the seperated form (especially in the southern language area), thus wegenmir instead of meinetwegen. In sense 2, however, both are equally common in the vernacular.
because of me, for my sakeDas ist alles meinetwegen passiert. All of this happened because of me.
as far as I am concerned (I don't mind if); for all I careMeinetwegen können Sie mitkommen. As far as I am concerned, you can come with us.