Can you imagine if the SP was as good as the MP? My God, what a game it would have been!
I don't know about all of you, but I played the crap out of ME1 & ME2, thinking each permutation would offer a fresh ending which would justify all the different paths I chose throughout.
I played ME3 SP just once. 
This saddens me, on your behalf. At the risk of coming across as patronising, I do have a tip for you and anyone else who struggles with the endings to the extent that they totally spoil your overall enjoyment of the SP game.
My way of dealing with the SP ending(s) was to remember the scene in Fletch, with the following dialogue:
Doc: You know, it's a shame about Ed.
Fletch: Oh it was. Yeah, it was really a shame. To go so suddenly like that.
Doc: He was dying for years.
Fletch: Sure but..... the end was very....... very sudden.
Doc: He was in intensive care for eight weeks.
Fletch: Yeah, but I mean the very end, when he actually died. That was extremely sudden.
I have nine different Shepards, all chilling out on the Citadel with their squads before the assault on the Illusive Man's base. Some of them may go on to play out the endgame (again), while others will just hang out in and around the Arena. If they do go on to the end, it is certain at this stage they will choose the Destroy option with no hesitation. Sorry EDI, casualty of war. Sorry Geth, your sacrifice will be remembered. Sorry Mass Relays, time to get you guys up and running again - shouldn't be too difficult, what with the entire galaxy united, right? In time, Shepard will rise. Maybe not in ME-Next, but sometime. Maybe with a hidden identity, ultimately forced out of retirement by a new threat to the galaxy. (Dark energy, anyone?) Just wait and see. That's how my imagination works anyway, no biggie if it never happens.
I, like most sane people, generally avoid entering debates about the Mass Effect endings, but every now and again I feel obliged to point out, for the benefit of anyone who was never actually aware of Casey Hudson's pre-release claims, it is possible to play the Trilogy and enjoy it from start to finish. It doesn't make you a moron, and you shouldn't feel ashamed. It is of course essential that you include the (free) Extended Cut dlc, and (misgivings about day one dlc notwithstanding) the From Ashes dlc opens up the possibility of having Javik with you on the Citadel (as well as all the other missions). The Citadel dlc is without any shadow of doubt the best dlc available for Mass Effect or any other game on the market. It's that good - even the NPC dialogue is better than that of most games' main characters.
For those of you who were aware of Casey Hudson's pre-release claims, I can only sympathise. And I accept that there probably is no getting over that experience, which must have been discombobulating. I wasn't, as I cut myself off from the outside world in general, and internet in particular, so that I could experience the game without the opinions of others having any bearing on my enjoyment. I'll do exactly the same thing on day of release next time too.
As this thread is primarily about MP, I will also add that I was completely and utterly against the very concept of an RPG including MP. Then I played it. I was wrong. So totally wrong.