My son died recently--I am not on speaking terms with his wife--how can I find out the details of his will?

First are you sure there is a will ? Has an estate been entered into probate ? Depending on how he owned things they may not even be a will ( or a need for one)
If house was jointly owned, if all bank accounts where joint and so on, she would merely just now be the owner of everything.

If there is a will, it will be filed in probate court and if you have a claim or are part of the will, you can see a copy though the courts