Steven,
First, I must say that I'm sorry you have to deal with this during the holidays because I personally think it makes it even worse since you are thinking how you want to be close with someone and share certain moments very often. So, one positive side is that the holidays are now over, and this will make things easier -- at least, that's what I'm hoping.
Second, once you love someone, it hurts a great deal to lose that person. It hurts like you will die at any moment from the pain, and although it's tempting to drink, smoke, f***, or whatever else the pain away, you have to embrace this terrible pain to move forward. The pain will dull, and if handled properly will completely subside with enough time. It sounds like you're already doing things that help you move forward -- talking with family about what happened. I would also recommend that you talk with friends . . . well, actually, talk with anyone that will listen to you -- even strangers (I did, and strangers sometimes had very poignant things to say, especially since some of my friends were tired of hearing the same story). In addition, when you don't feel like doing anything, don't make yourself do anything -- allow yourself to be sad, cry every day if you have to (do it in the shower if you don't anyone to know).
Third, I would highly recommend seeing a counselor so that you do move forward in the quickest time possible. Especially for men, it can be hard to fully express all your emotions if you are not in a controlled, safe, encouraging environment. Likewise, the professional counselor will give you professional opinions of your ex's behavior and your own, not to mention effective ways of moving forward. Also being from a family that doesn't have faith in counselors, I understand the hesitation, but it's well worth it.
Fourth, as for the running, I also stopped right before we broke up and still haven't gotten back ( a month after ). One thing that I have been able to do is walk, which has the same mind-clearing benefits and will keep you in good enough shape not to lose everything. I just felt too tired to run, although I probably will start again next week.
Finally, don't blame yourself. I did the same thing, mainly because I loved my ex and felt that my ex knew me very well, so I figured if he thought I was responsible, I must have been in some way. However, when dealing with people who have psychological issues, as your mother said, you can't really make sense of it. I know it's hard to believe now, but there is light at the end, and unlike the end of a 27-year relationship, it might not take a whole year to get over it . . . or, it might; but, either way, you have many years left and many other woman to meet and possibly love. Good luck.