A source tells ET that the pop star is "doing really well" right now, and that her friends and family are all "incredibly relieved" to see her happy and thriving since leaving treatment.
"When she was in the facility, Britney spoke nonstop about going home and seeing her boys, and that is the very first thing she did," the source says of Spears, who shares two kids -- Sean, 13, and Jayden, 12 -- with ex-husband Kevin Federline. "She wants to spend every moment she can with them and can't wait for their summer break to begin."
"While everyone warned her to take it slow and give herself time in the facility, Britney missed her routine and just being in her own bed," the source adds. "She has come such a long way. She's had years of therapy and care, and this time, she knew the signs when she needed help. With the support of [boyfriend] Sam Asghari and her father [Jamie Spears] she made the decision to get help and she's very proud of that."
The source adds that Spears has a solid support system in place, and knows when it's time to slow down.
"With that said, she is also aware of how quickly things can turn, so she's agreed to continue to take care of herself," the source says. "She is so excited to get back to her regular workout routine and eating habits. She feels in a very good place again and has made so much progress. She raves about Sam and appreciates his constant support. They are so in love and seem to get closer every day."
ET learned in April that Spears had checked herself into a health facility. An additional source told ET at the time that she made the decision in order to deal with the tremendous stress she's been having over her father's current health crisis.
The check-in came just a few weeks after she put her career on an indefinite hiatus, postponing her album and putting her Britney: Domination show at Park Theater at the Park MGM resort in Las Vegas on hold before it even began.