"I have been terrified since Nick has passed, as a single mother, of getting this virus and now I am one step closer to safety," she wrote.
Cordero died on July 5 after facing complications from COVID-19 for three months. He was 41.
Cordero left behind Kloots and their 1-year-old son, Elvis.
Kloots said Elvis was with her when she received her vaccine.
Kloots also responded to backlash she said she received about getting a vaccine dose before being in an eligible group.
"Vaccine shaming should not happen," Kloots said in a video posted to her Instagram stories. "Anyone that gets it [the vaccine], we should be celebrating."
She stressed that the extra doses left over at the vaccination site Friday night would have expired and been discarded.
"A surviving single mother ... deserves to have an extra vaccine that would've been thrown in the trash," Kloots said.
"This was a very emotional experience for me. I was perfectly fine being turned away tonight if that was the case," she said, adding that the staff was "happy to have people there waiting with willing arms."
Over 41.9 million Americans have received one or more doses of a COVID-19 vaccine, according to the Centers for Disease Control and Prevention.