Should i just ignore what he said?

Im 21 and have a bf of the same age. we've been dating less than a year but live together and im almost three months pregnant. i recently found out that he has four other children ( maury episode i know) three of them are with a girl he was with for 5 yrs and knew for 7. he tells me that he still loves her but just like a friend or sister because of all theyve been through and shes the mother of his kids but he doesnt love her like to kiss or have sex with or that kind of love relationship. but today he said while crying because she was mean to him. "i love her. no u dont understand i love her a lot. a lot. and i dont care if u get mad cuz i say that cuz its true". he then cleared up that only love like a friend... i dont know what to think i wish he had told me the truth sooner and i wish i wasnt pregnant {i used to feel happy about the pregnancy} i love him and i want to believe him and trust him but im scared im making a mistake by doing that and im scared that in his heart im allways going to be second.