Basically, would I play the second dotted quarter (highlighted)? I am thinking yes, because the fingering of a 1 on the B is only possible if you release the D.
This is not a tie. The line over the melody containing the highlighted D (or B if this is in treble clef, although I think it's bass clef) notes is a slur, indicating that this is a phrase. It's a purely stylistic marking: it tells you how to phrase the music, and to some extent how to pedal this piece. However, the low notes (one ledger line below the staff) are tied.
This is clearly not a tie since that would make the first note gratuitiously too short to catch up. Generally, ties must be between adjacent notes. There is one notable exception, "arpeggio ties", often in combination with piano pedaling. I thought they were named "Rachmaninov ties" but a web search does not appear to support that contention. Maybe they run under some different composer's name.