Need help in creating a file in required format form another existing file

I have a text file with contents like this:

a,b,c,
d~e,f,g,h~i,j
,k,l,m~n,o,p,q~

I need to convert this file into this format unix shell script commands:

a,b,c,d~
e,f,g,h~
i,j,k,l,m~
n,o,p,q~

as you may have noticed, I need to retain the ~ signs at the end.

Any help is greatly appreciated.