If a tree on my property fall on neighbors property can he sue me personally
A tree that was seemingly healthy and had no indication of falling over is covered under "act of God" and the neighbor cannot really sue you for it being there.
They can graciously ask you to please help remove the tree, but really, you cannot control nature and have no control over the tree.
If the neighbor has addressed concerns over the tree and you did nothing to help relieve the concerns then there may be some form of liability if the neighbor can prove that their concerns were founded.
If a part of your tree hung over their property, they could have removed it at any time on their own, relieving themselves from future anguish. If they did not do this, you cannot be held responsible for the tree falling.
In a nutshell, if you were not negligent then you are not responsible. If the tree was healthy and fell due to some storm or unforeseen factor then you cannot be held responsible.
http://realtytimes.com/rtpages/20031006_treefall.htm
