"For over 25 years i have loved and supported you, and I'm not about to stop," he wrote, while text over the image read, "I love you. I'm proud of your. And I support you. Always." He also added a rainbow emoji.
Braunwyn also shared a photo to her Instagram Story with another woman, which she added heart and rainbow flag emojis to. PEOPLE confirmed the woman is Windham-Burke's girlfriend, Kris.
The reality TV star announced on Wednesday that she's a lesbian, a statement 42 years in the making.
"I'm finally comfortable enough to say: I like women. I'm gay. I'm a member of the LGBTQIA+ community. I'm a lesbian," she proclaimed in a new interview with GLAAD. "And it has taken me 42 years to say that, but I'm so proud of where I am right now and I'm so happy where I am. To be able to be comfortable in my own skin after so long is just so nice."
She added she's "still getting used to" the lesbian label. "This isn't something that's new," she said. "I've always known it, but it took me, personally, 42 years to be comfortable enough in my own skin to say that."
Windham-Burke has been open about her sobriety journey this season on the Bravo show and she says there's definitely a correlation between getting sober and her self-acceptance of her sexuality.
"I know that when you get sober and you start doing the work that goes into that, you start realizing a lot of the reasons you drank had to do with who you were on the inside ... this sort of became something that I didn't want to hide anymore and I didn't want to keep a secret anymore," she explained. "I wanna be able to go out to dinner with whoever I want without judgment. As long as my husband's okay and the person I was dating's okay and knows everything, I didn't wanna have to hide this anymore."
She added that, after getting sober and having "some really intimate nights with people that I cared about" to rid her of any doubt about her sexuality. "I'm seeing someone right now and after the first few times I was with her, I was like, there's not a doubt in my head this is where I belong."
Windham-Burke also said she started thinking more about her sexuality following a much-talked about makeout session with former costar Tamra Judge on their reality show.
"I had a scene with Tamra that everyone kind of talked about," she explained. "When we were getting ready for the reunion I was talking to a producer that I trust a lot, his name was James, and he said, 'How do you feel about this? Was it a drunken mistake or is this a part of who you are?' And I said, 'This is who I am.'"
"When I went to the reunion last year I kind of started baby-stepping into, 'This is who I am. I like women,'" she added, "kinda testing the waters with my friends, my cast, my family."
Braunwyn is still married to husband Burke, with whom she shares seven children whose ages range from two to 20. They still live together and, despite Windham-Burke's coming out and new relationship with a woman, don't plan on divorcing.
"Honestly, we are in uncharted territory. I don't have a role model for this. I don't have anyone to go to for answers. So right now, we're just doing it our own way," she explained. "You know, Sean and I are still married. I plan on staying married. We're not sleeping in the same bedroom right now, but we're in the same house, we're raising the kids together. He's my best friend. He knows the girl I'm dating, her name is Kris. I mean, we go to parties together!"
"She came over the other night, hung out with the family, had dinner with us," she added. "I mean, it's only as weird as you make it ... I don't know why it's working."
"I love Sean. I love him dearly, he is my person, he is my family," she continued. "But I'm not attracted to men and I never have been. I love him and, over the course of 20 years, I learned to love him like that ... and this has been a topic of conversation between us in the household ... but I've never looked at men that way."
The 43-year-old reality start said she hopes her story will help people in a similar situation -- telling GLAAD, "Hopefully, when this comes out, there's gonna be other people that say, 'Oh hey, I can relate to this!' or 'Hey, thank you!' and that will make it better."