That blows. The worst thing to say or imply to a sick (depressed person) is that they shouldn't be sick because everyone else is suffering due to their being sick (which, duh, they wish they could be better but didn't ask for the disease and it takes time to manage since it's currently incurable). Guilt sucks big time! I'm constantly apologizing to my mate for outbursts and sometimes he gets angry right back and defends himself in the midst of it. I feel terrible that I can't seem to get my moods under control or sleep regularly, etc.
Family dynamics make it much worse when yours or your spouse's parents are nearby and talking about things they know nothing about just because they want you to be suddenly "normal" which I doubt they are anyway...they just have different problems in their personality and behavior if not mental chemistry (i.e. manipulation).
Best decision of my life was to move away from my family/relatives etc. Could not deal with all of their problems in addition to my own. But after you have kids, things get more complicated. You worry about their well being, if you're screwing them up, if there are others around to watch them when you're feeling bad, etc. Remember, take as much time as you need to get your meds sorted out and to feel better. Quick, yet temporary fixes are not in anyone's best interest long term. If you get better over the course of a year and are on meds that balance you out, you have the whole rest of your kids' childhood to make up for this difficult period (because this really isn't your fault and your doing your very best to get well). The kids will likely remember it as a blip on the radar when mom was majorly stressed out, but be happy to have you well for the rest of the years you spend together.
My mom was depressed and sleeping all the time for much of my childhood. I just thought she was physically sick so I'd always try to visit her and cheer her up and help her with chores. I never held it against her because I loved her and I knew she wasn't upset at me and that she wanted to feel better and was doing the best she could. I was closer to her than my dad (who was constantly working and incredibly selfish) even though her problems were more obvious than my dad's to the outside world.
So, all this to say, in the long run, this can all be sorted out and your kids will still love you so long as you keep working on getting better. The stresses in your life are not helping, however. Not sure what to suggest except for avoid seeing the in-laws or your parents as much as possible during this process. Tell your husband he can go by himself and confront him if he commits you to going somewhere without your permission in a firm, non-emotional way if possible. Explain to him you have other plans and he can go and if the kids want to come, they can also. This is what my mom had to do with my dad and his mother because the woman drives even absurdly kind people insane.