Shish I was on them initially for 6 months, but then my Dad was taken seriously ill so I stayed on them for a year in the end. Which ADs have you been given? They aren't usually difficult to come off, there is just about a fornight to four week weaning off period (depending on which ones you have) when you lower the dosage bit by bit.
I can't recommend counselling highly enough though, I am sure that's what made the difference for me and I felt so much better within a few weeks of starting the ADs and going to weekly counselling. In the counselling sessions you would be able to verbalise and let out all the emotions you are having about your family and about ds2 without judgement or recrimination and sometimes just talking about it all with an impartial third party helps you to get your head straight. Counsellors aren't there to tell you what to do or to judge, they are there to listen and if necessary gently guide you in the right direction.
I can't remember exactly when handling the two on my own started to feel easier. I think it was a gradual thing. It comes back to confidence really, you have to trust you can do it. Perhaps you could try having some days when you aim to do it by yourself but make sure someone is available to pop round if you feel you can't cope. Maybe just one day a week to begin with, or starting with just a morning or afternoon. There is nothing wrong with having help when you have a young baby. My Mum still pops round most days, sometime because I feel like I need help and sometime just for a coffee (having another adult to speak to after being in the house with two toddlers for a few hours can make all the difference).
I am just reading a book called 'What Mothers Do' which addresses precisely this problem. Historically women didn't raise children alone, all the women in the family did it together as a team effort and there was always plenty of advice, support and respite available within that circle of family. Its only relatively recently that women have been told they should be able to do it on their own and to be honest that is absolute rubbish, the more people around that love and care for little ones the more secure and settled they will be.
You should read the book actually its here on Amazon (I'm reading it while feeding dd) its all about what mothers actually do for their children, the way society views mothers and why it is that so many of us end up feeling negative about our achievements. I'm finding it really affirming and empowering, it reminds me to remind myself that I'm actually doing one of the hardest jobs in the world.
Also, don't be fooled by how well other people seem to be coping. The number of times I've made assumptions about other Mum's and how they are so cool, calm and organised only to find out later that they are only human and have problems and worries just like me. You don't know how often their Mum's/Grans/Sisters/Friends/DHs help them out. Everyone needs help sometimes.