LJC1979 go to the counselling with an open mind but resigned to it being over. VERY HARD but try.
Can you put into works what the parents living with you is all about. Do they need you to care for them or did it just come about as convenient for you/them etc? Were there any indications this was not working for him?
I can totally understand why your parents are angry, I would be if someone did this to my child, but you need to continue a 'working' arrangement with your husband in relation to your child.
I do wonder if there is someone else but I would not ask him since, if there is, he is not going to tell you.He may find the grass is not greener at all, but that may take time.
Could there be any other reason, like a breakdown?
Other do not know you because you have excluded them or they have excluded you, but you are reaching out to people and they are responding. You may not believe this but you are still young. You may meet someone else and perhaps even have another child. Your future could pan out completely differently. But you do need to grieve for this relationship.
You may even decide to have some counselling just for you and move forward that way.
Good luck. Keep talking.