Yes easily possible, you are not a beginner anymore with 2 half marathons under your belt last year.
I did a 10 week build up and felt it was fine, the normal cycle for a marathon is about 12 weeks if I remember correctly assuming you have a decent base (which you probably do).
The plan I followed is here -> viewtopic.php?t=13834
hope it gives you some ideas. I probably still have the spreadhseet if you want it. Most importantly start a training log, its always great seeing someone build up to a marathon.
Don't let the calories scare you, the amount of running you will be doing, you will lose weight.
Sorry your relationship didn't work out, you need to find one that compliments your training and doesn't take away from it