It is indeed a euphemistic or 'minced oath' version of "God love me" - with the verb, here, in the optative mood ("may God love me" or "as I hope God loves me") to invoke the Deity as guarantor of the speaker's sincerity. An analogue is "corblimey" < "God blame me", that is, May God impute sin to me (if I'm not speaking the truth).
- ADDED, 3/14/17: An anonymous reviewer suggests that blimey derives from blind me. That seems equally likely, and appears to be the sense in which the word was understood by late 19th-century observers.
It's 'cockney' in the broad sense of 'colloquial lower-class British', but it's not restricted to the area within earshot of Bow Bells and it's not rhyming slang.
In context, the three different words are just emphasizing each other. I wouldn't call them redundant, though: if you removed any of them, you wouldn't get across the same meaning.
If used separately, I'd say "horrific" is the worst of the bunch. (Certainly, its literal meaning is much worse than something that's just "awful"; but of course, not everyone1 uses such terms literally.) A horrific car accident probably involves pools of blood on the ground.
Second worst would be "terrible". A terrible car accident probably involves much crunching of vehicles, deformed metal all over the place, but if there is blood, it's not prominent.
The least worst2 of the three words is "awful"3. An awful car accident is worse than a fender-bender, certainly, but it might not have involved any injuries - well, except to your insurance premium.
[I'd interpret "Old friends whose past is always present" as something like "Old friends whose history is always on your mind when you're together", e.g. you can't think of Edna without remembering her bad divorce from her husband who also used to be your friend; or here's Bob, who looks amazing after he lost all that weight... 15 years ago; etc.]
1 Read: almost nobody
2 Yeah, yeah, I know, that's terrible.
3 In fact, it used to mean something like "awe-inspiring", but that was a long time ago.
Best Answer
It is a reference to Helen of Troy. She was said to be so beautiful that, when she was abducted, a fleet of a thousand ships set sail to win her back from Paris, sparking the Trojan Wars.