Your story reminds me of a lot of the similar thoughts and struggles I went through. For what it's worth, it took me three years to reach the point where a "switch flipped" and even then (hell, even now) it still takes time, patience, effort and a ton of humility.
Am I just better off alone so I don’t bring anyone into my mess of complete lack of humaning skills.
Probably. At least, that's my answer if you stay where you at now. Like you said yourself, you are still working on figuring out who the hell YOU are. How is someone else supposed to love you if even you don't know or love yourself? How could you love another? Someone with no boundaries and impulse actions sounds like a potentially unsafe person to be around, even in a non-intimate relationship.
To me, you sound as if you are overwhelmed. You listed a lot of things that are causing you angst and hanging over your head. Add to that all the shame and guilt we feel towards ourselves, and it really can feel as if we'd be better off living like a hermit in the mountains, far away from other humans.
But that's not the answer, and you know that. Moreover, you are a mother, and still a wife, a family member, a member of your community, work, even SI... people depend on you and love you, even in your broken state. And some of those people, such as your kids, really do deserve your best.
Here's a question for you. What do you want for your kids? Do you want your kids to grow up and feel the same way you do? Do you want them to lack boundaries? Do you want them to not love or even know themselves? Do you want them to hide away from others and shun things such as love and joy and elation? You are their model. Think about your own FOO and what was missing in your life. You said above that you never got the love, compassion and affection from your parents that you needed, wanted, deserved, and look at the damage it did to you. You can model a broken person to them, or you can model a healthy person. Even a person that is TRYING to be healthier is a better model than what you had as a kid.
You start small. You work up. You break things into pieces. And more than anything, you give yourself permission to fail.
Here are simple ideas of how to start feeling good about yourself. First things first... make a small, easy change that you feel you can keep up, and that you can accomplish. For example, start letting people ahead of you. If someone wants to merge into your lane, slow down and let them in. Hold the door for others. Let the lady with fewer things get ahead of you at the checkout lane. Let your family fill their plates first and then take yours. Move over on the bus. Offer to help clean up.
In doing so, what you are actually doing is thinking of others first, to your own detriment, but on a scale that you can manage, and most of all, feel good about. All of these small actions are a chance for you to do something selfless, and yet still positive. It allows you to be a good person, but not to expect praise or rewards in return. Every single time you take a small action like this, you need to stop and acknowledge it. You did something positive and good. You did something selfless. And more importantly, you've started to establish a pattern of doing small, selfless, good things. When you add up a bunch of small, selfless, good things, what do you get? Someone who does lots of good things. Over time, and this can happen so much faster than you might think, you will find that you are no longer doing these things because it's a conscious choice, rather, it becomes part of who you are. Over time, those actions change how you think, even how you react. Where someone pulling into your lane in traffic may have enraged you before, it now becomes so much less stressful. Doesn't less stress sound nice?
Don't get stuck on who you think you are or even what others tell you that you are. In the same way that it was your choice to have an affair and damn the consequences, now it is time to make a better choice. I'm not saying you need to become Mother Teresa. Just be the person you want to be. When you go to bed each night with the firm knowledge that you didn't lie to anyone today, didn't hurt anyone today, didn't do anything overtly selfish today, did your best at whatever you did and maintained your dignity and self-respect in everything you did... you sleep really well. And when people put you down, instead of crumbling and thinking about what an awful person you are, instead, you can look back at all the decent and meaningful things you've been doing and will continue to do. No one diminishes you when you love yourself.