Hi, I'm sorry your PND has become overwhelming. In your shoes, I'd definitely be back to the GP to talk about the medication and find something that doesnt risk having dramatic side effects. If counselling isnt helping, then you need extra help.
I'm sure your DH can see for himself hat thinking you want to put your child up for adoption is a dramatic statement, like a cry for help, and not necessarily something you actually want to happen.
I'm just thinking about your DH's reaction. Obviously I don't know anything about him, but I can see that after a year perhaps he is finding it hard work living with your depressive symptoms. And so walking away, and not reacting, maybe seemed like a good option. Perhaps based on previous conversations, he was worried about getting dragged down a rabbit hole, where he tries to persuade you that you don't really want to put your child up for adoption, and you don't mean the things you say it is the depression giving you these ideas, and then it gets very emotional which can be draining. Perhaps he is struggling to know how to support you and just needed a break from it.
Anyway, in your shoes I'd be trying to do everything under the sun to treat the PND. Show willing, try and sort the meds out.
Tomorrow, if your DH doesnt mention what you said about adoption, I wouldn't mention it again. Just leave it as one of those things you said when you were feeling very low. Focus on the things you can do to help yourself feel better, and give your DH a view of a pathway to recovery. And maybe even ask him how HE is feeling, if you have the energy, and sometimes knowing you arent alone feeling tired and depressed and overwhelmed can be somehow a relief.