As the events were unfolding, Miss Messner continued posting to the sub-Reddit.
She became increasingly panicked after an initial knock at the door turned out to be a false alarm.
"I am getting mixed reports of what is going on, I thought someone had called, as we thought we heard someone at the door, but maybe not."
One user posted saying they had called an ambulance to the correct address, to which she replied "THANK YOU".
Eventually the emergency services arrived to treat the woman and briefly took her into hospital.
After the incident, the woman joked with the Reddit saviour saying "as soon as I am paid this Thursday you will be getting gold :)"
Miss Messner said she felt helpless watching as her fiancee had a seizure in Dunedin while she was in Oakridge, Tennessee.
"The entire time I was terrified, I've never felt that terrified before.
"Sitting there watching her lips turn blue, frothing from the mouth, and twitching violently was the worst moment of my life."
She is keen to thank her partner's saviour in person to express how thankful she is.
"It was amazing, I'm so grateful.
"She's literally saved my fiancee's life."
Her brother David Neal frantically searched for a way to get help.
"I tried calling 911, about the time I said she was in New Zealand that was the extent that they said they could help, but they did wish me good luck," he said.
He then went online on the hunt for help, before a Kiwi on an online forum came to his aid.
"I went on Facebook, I looked all over for a go-between, and then I went on the New Zealand sub-Reddit and someone offered to help."
Mr Neal and his sister were able to talk to paramedics once they arrived to assist Miss Madill through the still-open Skype conversation.
Miss Messner hopes to move to New Zealand soon so the pair can get married.