To preface no I have never hurt a child, however I have hit my girlfriend's dog and screamed at/belittled him for existing and now he fears me and I just feel like shit because of it. 

My girlfriend's brother, his wife and their children are living with us for the time being, and we have allowed them to stay here for months. Long story short relationships are strained and their time here is beginning to run its course. 

They have a 10 month old boy and a 3 year old boy and I have been experiencing rapid intrusive thoughts as of late regarding their children and my girlfriend's dog. I simply just cannot excuse the urge to find them when they are in our house and terrify them/make them cry, while also combating thoughts of punting them and stomping them/throwing them.

 I know it sounds almost laughable (does it not?) but I'm being completely serious. When I am awoken by their crying and whining I literally envision myself storming out in a flurry of rage and putting an end to it one way or another.

The dog is a different story. He's the runt of the litter and I frequently belittle him and fuck with him, and when he is disobedient I take a direct approach and smack the fuck out of him multiple times before throwing him out. I end up feeling extremely guilty almost as soon as it happens and during the process. When I hear his feet tap on the floor and he paces back and forth whining even though he can go out when he pleases, he has food and water, it literally ENRAGES me. I also have laid in bed at night crafting methodical plans of making him go missing. 

He is now afraid of me and it pains me, I am beginning to think that I am incompatible with less conscious beings and children, which destroys me because I have always been great with kids and animals and have dreamed of becoming a loving father one day. My girlfriend wants children eventually and I am scared shitless that my mental health is just not compatible with them. 

I was abused by both my mother and father throughout my childhood on separate occasions, and it lasted many years. They never went after me together but they divorced when I was young and I went back and forth and had to deal with a lot of shit for a long time. Does this mean I'm fucked? Should I never have children? Should I just go to therapy?