yes....I would highly recommend seeking out a weekly therapy session with a person you find that you feel comfortable with -- and preferably someone who sees a lot of patients with abuse issues. There's nothing wrong with going to someone to help you heal these things and rid them (or lessen them) from your subconscious and your conscience.
From the type of unhealthy childhood environment you describe...there are probably a ton more other ways it is affecting your life that you are unaware of yet.
Seeking out the help of a professional therapist is one of the best things you can do to secure a future of happiness with less anxiety in your life. I liken it to a mentor relationship...a teacher if you will. We spend years and years of our lives in school, but yet rarely do people invest much time or study into learning how to live past the way they were raised or past our inherited disabilities. We just say "oh well" and "this is just the hand I've been dealt" ...and then accept it and move on instead of trying to "correct" our engrained negative/unhealthy perspectives and thoughts.
I am not a doc or anything, by a long shot, so take this with a grain of salt, but my impression of your short-lived relationships has some deeper roots beyond what you describe as the fears of harming them. Maybe there's underlying issues of commitment or intimacy stemming from the unhealthy relationships you lived among growing up. Perhaps seeing your mom, someone you trusted and loved, holding a knife to your father's neck has an influence too. Your child mind may have concluded that she must have not had total control of herself to do such a thing...and therefore making you fearful that if she possess such, then maybe you do too?
I'm not saying you should "blame" your parents, since for the most part most parents do the best they can, but it seems necessary that you accept that this was how you grew up and now that your an adult it's YOUR job to "re-wire" or fix what your parents weren't able to give and pass on to you.
I would also venture to guess that it's probably very important for you to learn to feel secure in your life, with your own self AND with those around you. You didn't have that sense of real security growing up so know it's time to give it to yourself. How? Well, that's where a good therapist would come in, but I think you need to have a bit of a chat with yourself about how rational your fears are. Do you really and truely think you are capable of such unconscience harm of another? Just that you are worrying SO much about harming someone tells me that it's not in you to hurt someone....and therefore these are irrational fears that, up to this point, you haven't learned to move past them.
One of my main issues is being SUPER critical of myself and degrading myself with waterfalls of negativity each day. One of the thousands of wonderful things I've learned from my very caring and wise therapist is that when I realize I am putting myself down (by for example: telling myself I'm a bad and worthless photographer b/c I didn't get a really great photo out of a difficult assignment)....is to say to myself, "STOP! Rewind. It's possible that I did the best job I could with what I was given and that the job I did was good enough."
Eventually, it will change to "I DID the best I could." But I'm not at that point that that statement is believable to me...so I say "It's possible" instead.
And it's helping...I am slowly learning to accept myself and realize that I deserve to be treated at least 'as good' as I treat others.
I'm telling you this b/c I think it can be very beneficial for you too. When you have these dreams and such or you are worrying about harming someone in your sleep....during your awake hours use the same type canceling technique.
Say, "STOP!!! It's possible I'm not a person capable of such a thing. It's possible that these fears are irrational ones. And that I am okay and safe...and so are my loved ones."
Make it your own, change it to fit your thoughts or situation. Continue telling yourself it's possible until you start to truely think it's possible and then change the wording to a more assertive 'matter-of-fact' statement like: "I am not capable of harming someone in my sleep. I am a good person and I feel secure in knowing that I will never act in such way."
Basically, you let thoughts 'brainwash' your mind into fearing these things and it's up to you to 'un-brainwash' yourself or 're-brainwash' yourself for the happiness and betterment of your future and in working toward becoming the person you want to be.
These are what therapists are for....to serve as guides to help us work toward become the people WE want to become and leading the lives we dreamed we would as children.
Lastly, in reference to your wondering about possibly dealing with some PTSD...yes, you very well may have develped some post-tramatic issues from what you've been through. Most only know PTSD by association with soldiers returning from a violent war so many think a person has to be witness to the most heinas of acts to develope PTSD, when in fact it doesn't take much in comparison. I for example developed PTSD issues and anxieties from daily and long-term harrassment by a former boss. Nearly 2 years later, and now in a WONDERFUL job with a fantastic boss....I am still dealing with visual and emotional flashbacks when someone of his build walks by my desk...and I react to anyone with even a hit of his personality or speach or negativity with the exact same emotions I did 2 years ago. It's hard at times, but I have to remind myself that the person in the present is NOT the person who caused so much trama in my life in the past.
Anyway, hugs and just remember to be gentle with yourself.
Jenna