so, he has a will so duh it doesn't all go to his wife unless there is no will or he states it in his will. I
A couple of things to consider.
First, the will only affects property that is in his probate estate. A lot of his property may not have gone to his estate. Any interest in property he owned jointly with his wife as tenants by the entirety (in those states, like NY, that recognize that form of ownership) or as joint tenants with a right of survivorship would have passed to her immediately on death and would not be part of his probate estate. Similarly, any bank accounts, CDs, investments, or insurance that he had named her as the beneficiary also go to her immediately when he died and would not be part of his probate estate. Finally, any assets that he had placed in trust (which is a common estate planning technique used in NY) would not be part of his probate estate either. Thus, even if you were given something in the will, that doesn't help you if the probate estate didn't have anything because all his assets passed in some manner that bypassed probate.
Second, just because he had a will made doesn't mean the will was submitted for probate. If his wife found the will and didn't like what it said, she may have destroyed it. If the will is not submitted to the court for probate, it's worthless. This is why when you make a will you want to leave that will with someone who you can be certain will actually file it for probate. If no will was submitted for probate, then his probate estate gets distributed under the state's intestate succession rules. If he had no kids, his wife would get everything under intestacy in most states.
The starting point is looking at the probate file, if probate was ever opened in the first place. It's a public record, so anyone can see it. If a will was submitted for probate, it would be there. The file would also list the assets of the probate estate, so you'd have an idea of what he had. Note that assets that bypass the probate estate won't be listed.
Is there a way to have his death investigated since his body was donated to science and picked up directly from their house?
As a practical matter, it is almost certainly too late for any autopsy to be done to see if there was any unnatural cause of death. You can contact law enforcement about your suspicions, but strange behavior alone isn't enough to get an investigation going without some proof that his death was other than by natural causes.
No one in the entire family was notified of his death. It's all very strange. Then to later find out that his wife had been cheating on him for years and years with other women it's so shocking...it's like something you'd see on Tru TV or something.
I can tell you that cheating spouses and families that are odds with each other are hardly uncommon. If the wife wasn't well liked by the rest of the family, she may not have felt any need to notify them of his death, whether out of grief, spite, or whatever. It's not the case that someone always rushes out to notify everyone when someone dies. Indeed, it's more common that the survivor tells the family and friends that she likes (or least doesn't dislike) and avoids contacting those she doesn't like because she doesn't want the aggravation of dealing with the ones that she doesn't have good relationships with on top of everything else.