The Brazilian supermodel and American football star split after 13 years of marriage last October.
"It's tough because you imagine your life was going to be a certain way, and you did everything you could, you know?" she told Vanity Fair magazine.
Bundchen also dismissed speculation about why the marriage had ended.
She described rumours that the breakup had happened after Brady returned to the NFL, despite previously announcing his retirement, as "very hurtful" and "the craziest thing" she had ever heard.
"What's been said is one piece of a much bigger puzzle. It's not so black and white," she told Vanity Fair.
"I have always cheered for him, and I would continue forever. If there's one person I want to be the happiest in the world, it's him, believe me. I want all his dreams to come true."
Brady, who won a record seven Super Bowl titles during his 23-season career, said last month he was retiring "for good".