My reading of that census was that William Butterly was Teresa's first husband, 2nd husband was surname Sheridan - both husbands deceased. Agree with your interpretation of the children's status..
Looks like Ballystruan townland may be missing from the online 1901 census at the moment...
Do you have birth certs for Patrick or any of his siblings ?
just wondering if the were living in the same part of Co. Dublin back then