I can relate. I started my MSc this past fall and did pretty well so I decided to take on 17 credits this spring, 9 grad and 8 undergrad. The semester started off as well..overwhelming. 2 weeks in, my best friend of 10 years died, at the age of 23. I have never felt this kind of pain. It is difficult to focus on school when you are suffering the loss of a loved one, and the best advice I can give is to take time, feel sad, let your emotions release, then work. If you feel overwhelmed, step away from your work and grieve. In my opinion, release those emotions whenever they overwhelm you; it will help. Make some time to grieve whenever the feeling comes along. The other thing to do is forgive yourself when you make mistakes; I've never been more distracted in my life and a few times I've made mistakes I wouldn't normally make. I'm learning to give my self a break; try to do that for yourself.
I hope this helps!