yep i agree - unless its necessary because there are kids involved - they are divorced & neither of need to still be so moved as to be constantly compelled to remain in touch with one another.
i get that divorce doesnt turn ever feel of endearment off but it wasnt enough to have held them together back when they made the decesion to get a divorce and go their seperate ways.
she obviously has other people to lean on during her illnesss and there are many other resources available to her for help doing the things she needs others to do for her.
any tech person can do tech related jobs no matter who has already worked on it prior to them becoming involved. and im sure there are other people in her life to offer their comfort & support to her during her times of need
it really is not for you to decide who she does or doesnt talk to amoungst her ex inlaws any more thsn its up to you to tell her who else she can talk to .. i understand how it must seem very inappropriate to you that she is doing it.. it has nothing to do with you to and there is no reason for you to take it upon yourself to invite yourself in & meddle into business that doesnt involve you..
i doubt there is much you can do to stop her from calling him on the anniversary of his brother dying and sending him birthday cards .. im not sure you can do amything to stop her from contining to do those things but he does not need to answer the phone nor does he need to stay on the phone and listen to her talk... he does not need to open the mail she sends him .. he only needs to look to see who sent it and pitch it in the garbage just like you do with all the junk mail you get.
if this is truely a major issue with you then its time for you to take a stand, spell it out to him in a way that will make it absolutely clear to him what options he has to choose between and how the choice he makes is going to unfold in the future outcome of your marriage .