28 years old having relationship problems with short tempered sig other father of both children. We fight and argue over every little thing , it all appears to be my fault , even if it's not somehow I have something to do with it . The question is how do I get through to someone who's always right and let them know that I don't appreciate the way I'm treated and that the fighting is no good for either baby , the one in my belly and the one who watches us quarrel?

Have you told this person exactly what you have said here? If trying to talk to him directly gets you nowhere, maybe try writing it down. Explain that when you try to discuss it, you both fall into repeating patterns of arguing and there is no resolution so you decided to write down what you wanted to say. This gives him a chance to think about it, hopefully, before responding. Avoid accusations that will only put him on the defensive and won't open communication.
Try to determine just what the arguing is really about... control, hurt, respect, stress, etc.. You might have to take it issue by issue and come to a decision about each thing that seems to be causing an upset to the relationship.