Yesterday, I received a phone call from Niki (who is related to Alexopoulos). She had gone north, she though I was still in Corfu. She told me he was alone and generally depressed. He said that he has bitterly regretted making this house. WHETHER SMALL OR BIG, houses need happy voices, both of children and adults.
Remarks about the translation
"του Αλεξοπουλου." means that she is related to that guy somehow. Probably his daughter or girlfriend. It's not clear so I'll translate this as a parenthetical sentence.
"She went north" could also be translated as any of the following "He/She went north/uphill"
"She told me" could also be "He told me".
"He said that he had" could also be and combination of "He/She said that he/she had".