So I am feeling kinda depressed at the mo

Everythings going
fine with the boys and the pregnancy but I
am beginning to wonder if I am soon to be
a single mum of three.
I have been with chris for 4 and a half
years, he had a car accident 3 years ago
and has been on crutches ever since
because he broke his femur. He is finally
getting much stronger and its actually
mending so things should be good. But its
not, he started to suffer with depression
about a year ago, it was a nightmare at
times but I always put up with it because
I loved him and tried to understand as
much as I could.
Thing is, I dont know how much I can
handle anymore I thought when his leg
started to get better he would slowly
start to feel better with himself as he
would be able to do more, but its not the
case. If anything its worse! He's
constantly moody with me and the kids. He
shouts at me all of the time and swears
and just generally treats me like sh**.
He never goes to bed till about 3 in the
morning and then sleeps all day and leaves
me to sort out the kids and stuff. when he
does get up all he does is just sleep on
the chair.
I have spoke about it with him loads of
times and usually he says he will try to
make things better, and usually they are
better for about a month and then it just
goes crappy again. We talked the other day
and he said he would make an effort to go
to bed earlier and get up and stuff but
hes done nothing! hes in bed now and its
like 3pm. I just feel like a door mat
running after him all the time.
I just dont know what to do anymore... I
cry about it all the time. My lifes so
messed up I dont know how I am supposed to
stay with him as I cant see it changing
but whats the alterative being a single
mum of three young kids....