Definitely the former. While a priest could potentially say min son (and I suppose that would be a lot more common in certain denominations, like the catholic church which is small in Sweden), I do not think a priest would ever say jag älskar dig as a priest.
Is there a reason why it wouldn't accept "dej" as an alternative spelling? I've seen "dej" and "mej" used a lot in Swedish and I thought they were interchangeable?
dej is a lot less formal but it's absolutely fine in any colloquial text, and quite a lot of prose as well. It's usually accepted throughout the course, so I'm sure it's just missing.
There's a problem with the dictation exercises, we can't get any spelling variation accepted in those. We try to accept dej etc in translation exercises (it's still missing in some places) but there's no way for us to add it in the listen and type exercises.
Oh, I thought that grammatically only "mig" and "dig" are correct in spelling, whereas "mej" and "dej" just the way to pronounce them (and if written, bad grammar and very informal). Oops? Maybe I'm just old already, or had a very strict teacher back in the days. xD
Ah, right. I thought it had been fixed by now, but I must have dreamt that...
In isolation, "dey" is not a bad approximation in English. (Loads of examples here: https://forvo.com/search/dig/sv/)
But in practice, the initial d often tends to merge with an ending consonant of the previous word - especially verbs ending in r. So älskar dig has a tendency to become something like älskarig, especially in some regions.
Could I say something like: "Min familj är liten i antal men stor i kärlek"? :) Tack så mycket.