firstly,welcome to the forum
sorry to read about your husbands death,it must have been so terrible for you and i can understand your pls getting worse after such a blow.
i did have pt for a few years but due to exercise intolerance and the fact that they do it just to keep you going(it can not really improve things)i decided to call it a day.
you can do simple stretching to relieve spasms and stiffness,light exercise to keep strength going (though i told my pt i get enough exercise trying to cope doing day to day things that end up wiping me out)
any small repetative movement that pushes the muscle or limb a bit is ok,its important not to push yourself too hard so as to end up a blubbering,crunched up wreck(been there,done that
by the way,i am now 10yrs with pls. still walking with aids though not as active as i would like to be.
we are a fairly happy bunch here and you will find lots of support and info.