pc - is there anyone in rl you can talk to? You sound like you are going through a really hard time, but you are in therapy which takes a lot of courage, especially if you have to face some painful things. But you are doing it, so that tells me you are a very strong person and should be proud of yourself. I dont know what to advise, but maybe you need to go with the feeling of sadness and have a wallow, to get it out of your head, does that make any sense???
Talk to the samaritans if you need a RL ear, ive spoken to them in the past and they really helped me.
When do you see your therapist again? What can you do to tide you over, or can you get in touch before hand? Are you on medication? Perhaps this needs looking at.
I think MN has been a bit slow today too, no barneys to lurk on - always a bummer
Are you due for a period by any chance? i know this sounds trite and i would never dream of asking a woman this usually, but sometimes when i am due, i get the whole sadness thing appear from no-where. Just wondered? Do you know why you feel like this at the moment?
Good luck, hang on in there xxx