Let's switch things up a bit. Maggie didn't suffer from postpartum depression (assuming that's why she left in the 1st place). Jack's more of a deadbeat. Jack leaves, and Maggie's the one who raised Matt.

Matt's accident still happens. Maggie isn't involved with any of the Irish Mob, so she lives. And if the Matt we know is anything like his mother, Maggie is gonna be damned if she doesn't put every ounce of effort in helping her son in any way she can.