Long story need advice !

I recently heard my mom and sister talking over FaceTime about me. I work at my sisters store but she has been making me babysit her daughter for the past three months ( I thought it would be temporary and I would be going back to working at her store). Anway I heard my sister go "she's slacking" to which my mom replies "I know she's being a real pain in the ass".  So hormonal me had a total melt down,busted down the door and cursed them out! It really hurt my feelings that my own mother and sister would talk behind my back  especially about me "slacking" when I'm 7 months pregnant with my first and try my hardest to be active while watching her 2 year old daughter ! This has been a week ago and things are still not settled, it has given me such unneeded stress and what makes matters worst is my husband and I have been living with my parents because we are waiting to get into our house in July.  I apologized to my mom for cursing at her and all she said was "you know I talk about everyone" "you are slacking, your hearts not in it ". I was seriously speechless ....I watch my sisters baby ...I didn't sign up for this, especially at 7 months pregnant. I know many people have toddlers during pregnancy but I never once complained about my lack of sleep/aches and pains to my sister because I knew it would lead to a argument.  I'm thankful my husband has a great job and I don't have to work if I don't want to which is why I have been just working with my sister temporally until the baby comes. But I pretty much want to just stop working for her now and focus on moving/ getting the baby's stuff in order. Especially after I see how they feel/treat me. My showers this Sunday and my mom and sister are hosting it and I hate that we haven't made up but at this point I don't even want to seeing their attitude/ feelings towards me haven't changed. I feel like at this point in my life I need to be the best I can be and feel the best I can feel and all they do is make me feel bad about myself ...I think once I move out that I'm going to pretty much excommunicate them and focus on being happy with my baby and husband ...Its unfortunate but I really don't want/need negativity around me and my new family. Sorry so long! What do you think? Am I wrong for feeling this way? I need to add that my mom has always been like this...I thought our relationship has gotten better since my teenage years but I guess I was wrong!