I know just how you feel. I live with my daughter away from my home state and don't have any friends here. She is in the military and took leave for 20 days and went to our home state. It was rough. I had to stay home because we have two cats and didn't have anyone to take care of them.
I think you are on the right track planning on staying busy. Is there public transportation you can take to your yoga class? I know for me when I am down I exercise on my WII and that helps built endorphins. I know it is really hard when you are not motivated but do what you can. I also recommend one of the previous suggestion. Watch some funny movies. I am not a big TV watcher but I watched a few comedies while my daughter was gone and that helped. There is nothing wrong with asking your kids to say home one night and have a game night or something too. I know my kids are a big part of my recovery and therapy, any interaction with them makes me happy.
Good luck! Just remember that we are all here for you. Remember there is a chat room you can drop in for some social talk or support.