Stressing!! How do I ???

So before you bash me, please listen..I'm only human.. I was on depo for 3 months, I was suppose to go back and get my next shot...but I totally forgot. I had a lot going on, my dad just died and I been with family which lives in a different state than me. My boyfriend & I had sex and came in me a little bit. I didn't think about the plan B pill until a week later when I discussed w/ my bestfriend she told me to buy it. Come to find out a week is to late to take it after intercourse. I go to the DR and I'm pregnant. How do I tell my BF this? We wasn't trying to get pregnant and I don't believe in Abortion. I'm nervous.