Dear Chin Up~
Welcome to the Forums again, I hope they were some use before.
Sophie_M has given good advice and links, however I thought it was worth mentioning something else.
You said yourself that straight after having your baby you left an abusive relationship wiht nothing. It is now 18 months on and you have actually done something quite impressive, you have stuck it out, been resourceful enough to find a place to stay, manged finances and most important love your child.
Instead of realizing this great feat sadly you say
I hate where I have let my life go. I know I put myself here and I take
responsibility for that. But it only makes the feeling worse.
Ir really is not down to you at all, it is down to the abuser in the relationship that instead of loving and supporting you in early motherhood caused you to leave. You have survived that!
You feel guilty there is nothing you are able to do for you, that your time and resources go into looking after your child and htat's it. This is entirely natural and caused by having to try to be a mum in isolation. Mothers need help, it's that simple. And do sometime wish that were not mums. It's OK.
There are support groups and some helpful societies for those in your situation, and they are in every state. Our 24/7 Help Line Sophie mentioned above may know of one, or where another organisation is that does, it varies from place to place.
You did mention not talking to the the ones you love, maybe parents, maybe others. I was in the same boat myself, suicidal and ill having been invalided out of my occupation. It was a very long time before I opened up to anyone about my suicidal thoughts and actions, particularly family.
When I finally did talk to one person a load was lifted, I was no longer truly alone, and things improved until I'm now good.
In parting please believe the love you bear your child, not your internal struggle, is what your child will feel, and of course will always love you back.
Please make a few phone calls and let us know how you go