Hello Firsttimer, I'm sorry you are feeling so low.
I think a lot of what you are saying will resonate with many of us on here. I think it is hardest when it's all new and you are still trying to find your way through. Things can and do get better, although I'm not going to tell you it will get easier, because for many of us that simply isn't the case, but you will find a way through and find a way that works for you and your family. It is hard not to grieve for the life you thought you were going to have and the future you hoped for for your dd, but just because it's going to be different, doesn't mean it's not going to be a good life.
I speak from experience, as someone else who has had a child diagnosed with special needs and been diagnosed with MS myself within the last 18 months. I have good days and bad days, but try to focus on the things we can do, rather than those we can't. It's not always easy, I don't always manage it, but I hope think I'm getting better at it. I find planning things to look forward to helps, even if it's just a trip to a local country park for a walk and a cup of coffee or picnic at the weekend.
I know what you mean about the stress pushing you apart rather than bringing you together - you have to work on that though. Try to make time to enjoy each other's company without having to talk about or deal with the crap. A walk, a picnic, even just watching a film together in the evening - none of it costs money, but the time and space to just be together is priceless and helps to remind you what you loved about each other in the first place.
With everything that you have been and are going through, it's important to make time and space for yourself as well. No-one can be all things to all people at the best of times, let alone without taking some time for themselves. When I felt like you I started shoving dd in the pushchair and walking. I started small, just a walk around the park, then the block etc. I bought myself a pedometer and built it up until I was doing my 10,000 steps a day. It helped me to find some peace from the constant noise in my head arising from the chaos that was our life and had the added bonus of working off some stress and excess weight and improving my fitness at the same time. Find whatever works for you, be it walking, swimming, gym or an exercise class.
If you are seriously at the point of not being able to even contemplate doing that, maybe a chat with your GP would be an idea. I know you said you are having some counselling, but you may need some anti-depressants to help lift you enough to get going. I have had to do this in the past. I was very anti and really didn't want to take them, but it was the best thing I ever did, as I couldn't change anything until I took control and I couldn't take control until I had some help with the stress and anxiety.
I second iwantto's advice as well. Homestart can be a huge help, either in practical terms or just by having another adult to talk things through with or even spend some time not talking about all the day to day stress and problems but having a cuppa and chat about this and that - which is something 'other people' take for granted. My sister is a Homestart volunteer and she helps in lots of ways, from looking after children so their mum can have a nice long bath or walk or pop to the shops, to doing the shopping for them, to just having a cuppa and a chat.
Another idea is to approach your local SureStart Centre and ask if there is a SNs support group in your area. Our SureStart runs one once a week, just a coffee and chat, some emotional support and practical advice based on others' experiences really, but it all helps to make you feel less isolated.
Finally stick around and keep posting on here, join us on the Friday night thread to either chat about your week or sound off as necessary. MNSN has really helped a lot of us to not feel so isolated and slowly start to make sense of things and move forwards, it is an incredibly supportive and friendly place.