LaContessa, just to reassure you a bit (I'm training in all this stuff these days!), 1 in 5 mothers will have some sort of baby bonding difficulty and for the overwhelming majority, their babies will be securely attached to them at 18 months.
Most of the research on long-term difficulties usually says that it is untreated severe, long lasting depression in the context of personal and social adversity that leads to less positive outcomes.
And what we have to remember, as you've said here, is none of us chose this. It's not our fault. We find ourselves in a situation, and we do the best we can, with the resources available to us at any given moment time. There's no more anyone can ask of any mother, in any situation, at any time.
The other critical point here is that children's attachment comes out of being loved (being responded to, taken care of, fed, cuddled, growing up with a sense of security) rather than a mother's FEELINGS. Love, in this context, isn't a feeling so much as an action, hence being told to fake it til you make it. It took me a long time to get this.
However, if you are in a very dark place and you can't look at or respond to your child, it is better that you, as a mother prioritise self-care and treat that state of being in whatever way can return some equilibrium as soon as possible while allowing the baby to be minded by someone who can offer that. This is not an act of selfishness. It is an act of courage and love and deep wisdom.