Things are frosty!

Ben Affleck and Jennifer Garner have been doing their best to co-parent their three children in the wake of their shocking split, but from the looks of it, it's a little more of a challenge than either of them realized. The two spent time together with their brood on Sunday, and the actress looked visibly tense around her ex. Earlier in the day they went to church together with the kids, though the two kept their distance. Something notable, however -- Jen certainly stepped up her fashion game this week. Check out her sexy Sunday best!

Jen's revenge body is on point -- of course she's getting paid to work out, as she tones up for her upcoming role in the female action film Peppermint. Her "recipe for turning mom back into an action lady," as she dubbed a recent Instagram video of her workout regimen, is definitely working! With the intense exercise, she can channel her disappointment/jealousy/anger for Ben into muscles ...

A source tells X17:
    "Jen has taken the high road this whole time, but she's sick of it. She forced Ben back into outpatient rehab to prevent things from getting any worse, but she's heartbroken for their kids. For months, Ben was more focused on his new romance with Lindsay than he was on parenting, and Jen made it clear he needed to reprioritize and focus on the children and his sobriety. Consequently, Lindsay has been back in New York, and she's worried about the future of their relationship because she's not getting as much attention as she was earlier this summer."

They were in better spirits this morning, as we caught Ben arriving at his rehab facility and Jen grabbing coffee with a gal pal in Brentwood. Solo time seems a little less stressful!