It said his transgressions amounted to "very serious malpractice" and brought discredit to the medical profession.
"Dr H abused his position of trust as Mrs A's GP for his own sexual gratification," it said, noting a "significant power imbalance".
"She instinctively felt Dr H's behaviour was wrong and tried to resist it. However, she was vulnerable and he exploited this."
The exploitation was "cynical and deliberate", it said.
The HPDT cancelled his registration as a doctor, saying: "Public safety would not be adequately protected by an order of suspension."
He was also ordered to pay costs and disbursements totalling $66,440.
Graphic messages shown
The March hearing was shown pages of evidence detailing phone calls and text messages sent between the doctor and his lover, over multiple phones, many of them sexually graphic and explicit.
Doctor H sent up to 65 messages a day to Mrs A's phone number, many followed by phone calls, some from his surgery landline.
He also claimed Ms B's nickname was the same as a shortened version of Mrs A's first name. A name which appeared in many of the texts.
But he was found to have misled the tribunal.
"The tribunal does not rule out the possibility that a person called Ms B existed and was known to Dr H; but it does not accept as reliable Dr H's assertions that certain texts contained on the spreadsheet were intended for that person rather than Mrs A," it said.
He was also blamed for persuading Mrs A to corroborate his story.
"...Mrs A has become thoroughly caught up in an unbecoming and no doubt stressful attempt to mislead the tribunal about what really occurred. The tribunal infers this was as a result of pressure applied by Dr H."
It also described doctor H as "unwilling on many occasions to give specific answers", and highlighted other unreliable factors in his evidence, including a "willingness to manipulate" shown in his texts, and that he was prepared to swear an affidavit for the tribunal which contained "a completely inaccurate statement".