What hormones exactly make me/us act the way we do while pregnant?

I swear, being pregnant is like being on PMS constantly! I am usually a nice, swet person but lately Ive found myaself being really mean, accusing, saying the meanest things to people I love like my boyfriend, mother. I admit sometimes people arent that supportive of me in my time of need, but sometimes I am out of line the way I over-react. Like I told my boyfriend's friend last night to "get the eff out" for no reason other than I didnt want him there, nothing against him, just wanted him out. I also told my mother "what kind fo a mother are you?" and I've been talking so much smack about my boyfriend to a friend that I call her almost erevryday crying and now she confronted him (they used 2b close fiends). anyways I guess what i mean is, I lack self-control, have trouble managing my anger, say mean things I dont normally say that are very downright callous ad mean, and i have emotional and crying outbursts. Sometimes when i cry I can't stop. I know I'm under a lot of stress right