If I'm understanding what you're saying... It sounds as though you've found a great relationship with someone and you feel as though your issues are going to somehow destroy this relationship.
What you're fearing is perfectly understandable... Especially considering you mentioned you were 'essentially disowned' in the past. Also if I'm not mistaken, I'm picking up a hint or tone of paranoia in what you're saying. Your references to 'expecting impending doom' resound so closely to what I go through quite often. I have these wild thoughts that... "Everyone in my life must be out to get me, because I'm certainly not good enough for their love."
What this all does boil down to for me, is a massive lack of self value, acceptance, and esteem. It might be that way for you. I've spent a lot of time recently trying to convince myself that I am worth while... All of this work is helping to alleviate those 'crazy thoughts' as you called them.
My guess is, coop, that you are keeping these thoughts from your significant other. My first and foremost suggestion is: share these things with your significant other.
It's okay to tell them that you feel really dumb for saying it, but it'll help you put it in perspective... and to give voice to what you're thinking... No matter how crazy it is. It takes a blind leap of faith that your significant other will treat these feelings and thoughts with respect and help you through them.
A few months ago, I planned to meet an online friend for the first time. I've known him for years but we had never met. We're both straight men and have about as close of a friendship as two straight men can have considering online restrictions. We have seen each other through a lot of garbage in each of our lives. A few days before we met, I was having an absolute panic attack. I was making up in my head all sorts of things about him in my head and I finally had to talk to him about my stress of meeting him. I danced around it for a while, but eventually realized what my fears were about. I told him "I know this is going to sound ridiculous, and its totally un-called for, but I need to say this because I have to set my mind at ease."... I then went on to tell him that we couldn't do anything involving touch and absolutely nothing sexual when we met. Being that we were 2 straight men, it was totally unfounded... However there was still a part in my mind that was screaming in terror and needed to be set at ease about our meeting... I know this is different than your situation, but I'm giving you an example of how talking about things -- getting things out in the open -- can really help a lot.
Something else I would suggest to you is to Journal like crazy. Write down these crazy thoughts, keep a log of instances that you felt you did something wrong in a given situation... Then when you're in a clearer frame of mind later, have a look back at what you wrote, and see how you feel about it.
There is hope to overcome the aftereffects of abuse. I know it can seem like a very distant dream at times... but I believe it to be possible.
I hope what I've said is helpful to you... Good luck on finding that balance. You're not alone!