So hard not to be judgmental...but here I go:
(H)e was in a relationship with a terrible, alcoholic, and mentally-unstable woman. They got pregnant early in the relationship...
It sounds like there was all kinds of critical thought impairment going on in that previous relationship and it doesn't sound like he's accepted responsibility for any of it. Regardless of who posted that sister photo it's clear that this dude has an unacknowledged weakness for hot messes. Throw in some unsafe sex habits in his late 20's
, no less, and it's pretty clear that history is anxiously waiting to repeat itself.
Yes, ATU. It's time to flee.