Accident for no. 3

Hi, my husband and I have 2 children. We have a girl aged 1 and then a boy who is turning 5 months on April. We've tried to prevent another pregnancy but it happened. My husband don't mind but I am not physically and mentally ready. I have a thought of abortion but I feel so wrong and this baby is not something out of wedlock thingy. We are lawfully married. Do I really have a reason... Help advice