i agree with lulumama, kits, you know i have my share of problems just now, im driving DP to distraction, i honestly think he is as, if not more, depressed as i am just now. Even in my deepest darkest moments, and they can be pretty fucking grim, i can tell you with my hand on my heart that i am a good mother and manage really well with DD. So does my partner. I have been to the doctors, explained how i felt, really had some serious meltdowns, not once has she even asked or hinted that i may be struggling with DD. They will NOT take your children away from you, why would they?
I do happen to think college is a good idea, you don't have to be a hot shot lawyer or anything, you don't even have to do it for career advancement, you can do it for you - whatever floats your boat, if thats life painting (phwoooarrr naked men!) great, if its rocket science, great. You never know where it might lead. But one thing i do know, it will boost your confidence. You never know what your potential is, i left school having not even sat a single GCSE, nothing, when DD1 was 4 and i was 24, i went to college, they wouldnt let me do GCSEs they didnt think i would cope. It was a fair assesment, my track record was crap - last year, i picked up a PhD in biochemistry, everyone i know, including myself is gobsmacked. Of course my confidence is rock bottom just now, but one day, i intend to use that qualification. I was EXACTLY where you are now, didnt have the confidence or the desire to further my education. I am so glad i did it.
Go to the doctor, its the first step, get some counselling, possibly joint counselling. Does your DP work? If not, he needs to get a job, for his own sake, maybe he would benefit from college. I am a real education pusher, i think it can make such a difference.
You are a kind and caring person kits, what about nursing? midwifery? You have so much to offer, as well as being a great mum.