I think that what is happening is that you are at fresh start. On so many levels. Honestly, it feels almost like a 2nd chance for you. To really create the life you desire. One that lives your highest truths and then through that, the people and situations that arise for you will be what you want and need. And just to be clear, it is not as if you've done it wrong up until now. Certainly we know your son is nothing but right ;), and many lessons and experiences have brought you to this new found freedom. But I do get this feeling that you have in front of you, a brand new world in a way. And the point is not to be lonely. It is to begin manifesting all things that resonate with every level of your truth and being.
So try to view it like that, as opposed to lonely. Take some time to reflect on what a really great friendship would feel like and entail for you. Just as we all do this for a life long partner, you can do this for your friends as well. What kind of people do you desire to be able to spend friendly time with. To give and take and have equal share of energy? I am glad to hear you say that you realize the woman from class is a bit of a taker. Reason I am glad is because that demonstrates that you are not willing to accept anything less then real this time around. And you are recognizing when it is not. Although remember, there will always be people that offer varying levels of relationship to our life. She may just be a fun classmate and that is the only time you share with her.
In summary, I want you to continue working on YOU. Cultivating your truths and living them outwardly. By doing that, you will draw the right people in. You are lonely right now because it is the Holidays and you are still relearning to live without a partner. And I have heard many times that a lot of friendships end along with the divorce. But that is okay, b/c that means they were tied into that relationship and you don't need that.
2011 is going to be much different DancingAnne. It is filled with promise and partnership and friendships. But the key is to continue to self focus and keep putting the brighter, more focused, more light you out there to the world. You will get there. You are doing so well already.