You are not obligated to buy your wife (separated or not) a car OR pay on penny of the repairs. Perhaps she can get the OM to do that for her, or maybe her dad. The only concern would be if she's driving your child around in that car. Still, you're not obligated at all.
M:45 H:48 M:11 No kids BD:Sept'15 EA:Confirmed 1wk later PA: Oct'15 12 '15 2 wk R Just kidding, H wants NC 12 '15 H back w/OW 4 '15 R &still working on it