The couple called off their engagement in late November

Green said he's "heartbroken" to hear about Fox's breakup as she's "so excited" about her pregnancy

"I just want the best for her," Brian Austin Green said of his ex-wife

Fox shares her three boys — Noah, 12, Bodhi, 10, and Journey, 8 — with ex-husband Green

The actress is "devastated and very emotional" about the split, a source tells PEOPLE

Another source said the pair are both "ecstatic about the baby" and "really wanted this baby"

"They love each other but don't have compatible personalities," says a source about the on-off couple

Fox confirmed that she and now-former fiancé Kelly are expecting their first child together last month

The singer and Fox are expecting their first baby together, while Kelly is already dad to daughter Casie, 15