I feel bad for you Lemon. I can understand your exasperation.
At first,..just reading this post, I thought you were being pretty selfish worrying about yourself when there was a baby on the way. I then went and read your other thread,.....Wow, you have been a real stand-up kinda person. Seems as if you are trying really hard to be supportive, and just desiring to have smooth waters before any new issues are created.
I am not sure what I could say to steer you in the right direction, but I can say, I think you are entitled to your feelings, and they should be heard by those who care about you. You are definitely not crazy for feeling how you do.
Tell me, do L and B give you a feeling of 'fairness' outside social/romantic endeavours ? Do you feel they pull their weight in and around the house, paying bills, etc ? Have they taken anything for granted in that manner ?