Step mom rant

My boyfriend and I have been together for awhile and he has kids. I am new to the kid thing but I am winging it! The kids love me and we have such s good time together. I just get a lot of negativity from people. People comment how can I be with someone who has kids and people say stuff like don't you want your own family? It took my mom awhile to realize that if me and him are going to be together this is my family plus the kids that we have. My mom has really changed, she loves them. She buys them toys, lets them come over to swim, I just see the love and they love her. There is the one lady I work with and she is so rude. She makes the rudest comments. The other day I was talking about the kids with my cube mate and she overheard and said "you claim them kids don't you" and i said yes I do why wouldn't I ? She said "I wouldn't claim nobody's kids I'm not sure why you do". Or my supervisor will ask her if she would think I would like this left over sweets for my kids and she'll say she doesn't have any kids. I'm not sure why she is so interested in whether I claim them or not. When they are with me and my bf, cook for them, I bathe them, I dress them, I play with them, I do hair, I love them!!! I'm just about to snap because it's almost everyday and it's ridiculous! I'm not sure how I can handle this without going off .