Sounds to me like you're pretty up to speed on the whole MLC situation and what is left to us as the spouses on the outs.
Don't know all your sitch, but sounds like it could be MLC. Of course, she could just be fed up and ready for a change too. Not sure that it matters much in the end, your approach won't be much different.
You said many correct things, and that's good because that means you won't be like many who first come here all full of piss and vinegar wanting to save their dying marriage. If this is MLC, she just took off on the train through Hell and trust me, you don't want to ride on that puppy.
Separations don't scare me all that much, don't think they should you either. You will read of many on here who have their MLC'er still in the house and that doesn't sound like much fun to me. Of course being separated means finances and child visitation becomes an issue, but if she's reasonably sane other than her desire for her 4th grade boyfriend, you can probably work those things out.
One thing her being gone does, is lessen the chance that you will do stupid things to try to win her back. MLC'ers don't typically like to talk about their marriage. The marriage is the bad thing that made their life miserable, so talking about it is bad. They also don't really want to hear about how much you love them, because they don't love you right now and you might make them feel guilty for that. MLC'ers HATE guilty, they don't do it well at all.
Unconditional love is good. Do you know what it means? You love, you give, you are kind, you love some more, you give some more, you are kind some more, and they will reciprocate NONE of this. I repeat NONE. In fact, just to make it interesting they may choose to spew some toxic venom at you for being so good an loving unconditionally.
I sound kind of crazy, but that's ok, because everything about MLC is absolutely stark raving mad. In fact a good rule of thumb is to take whatever it is that you think you should do, flip it inside out and do that. I should make that a bumper sticker, but I digress.
There are many awesome people on this particular thread who have been through long, long, long stretches of MLC madness, and they will help you as long as you're not as thick as a brick. They have seen this time and time again, so they're really not looking to watch another poor soul go through the same agony all over again just because they refused to believe that not returning a phone call was a good idea. Listen to them, they will help and they will encourage you.
Read more. You've already done some it sounds like. Knowledge is helpful with MLC, particularly understanding how depression fits in to all this it seems. And prepare for madness, because you my friend have just chosen to climb down the rabbit hole and life will never be the same again.
More later.
Chin up.
Blessings,
Bill
"Don't tell me the sky is the limit when there are footprints on the moon."