Justin Theroux Avoids Jennifer Aniston at Birthday Bash for Jimmy Kimmel's Son

Jimmy Kimmel hosted a star-studded birthday party for his one-year-old son William on Saturday and former couple Justin Theroux and Jennifer Aniston were both invited.

However, according to PEOPLE there was thankfully no awkward interaction between the two as Theroux was spotted leaving just before Aniston arrived.

Before he left, Theroux posted a photo of himself holding Kimmel' son along with a heartfelt message.

"Happy ONE year birthday Billy!" he captioned the post. "A boy who in 365 days has done more for American national health care than we could all wish to do in our lifetimes. He doesn't even know yet how courageous he is. An honor to know him and his incredible and equally courageous parents."

William was born with tetralogy of Fallot with pulmonary atresia, causing him to turn purple within hours of him being born. He had to undergo open-heart surgery at just three days old along with a second surgery seven months later, making a full recovery from both.

A source close to Aniston gave an update on the Friends actress to PEOPLE after the party.

"Jen is doing well," the source said. "She is keeping busy and moving on with her life."

The couple announced their breakup via a statement back in February.

"In an effort to reduce any further speculation, we have decided to announce our separation. This decision was mutual and lovingly made at the end of last year. We are two best friends who have decided to part ways as a couple, but look forward to continuing our cherished friendship," the statement read, via E! News.

"Normally we would do this privately, but given that the gossip industry cannot resist an opportunity to speculate and invent, we wanted to convey the truth directly," the statement continued. "Whatever else is printed about us that is not directly from us, is someone else's fictional narrative. Above all, we are determined to maintain the deep respect and love that we have for one another."

As of mid-March, Theroux was "still heartbroken" over the split, according to a source at Entertainment Tonight. He has since been spotted with 25-year-old model Petra Collins, though neither have confirmed their officially an item.

On the other hand, Aniston has reportedly been staying busy with her social and professional life.

"Since her split from Justin, Jen is doing fine," a source told PEOPLE. "Justin has moved on with his life in N.Y.C." while "Jen still enjoys hers in L.A."

"She loves socializing with friends," the source shared. "Her friends always invite her out and to parties. Jen has a very caring group of friends that take care of her."