This is an issue that many women face and it's a challenging one...
Birth Control - gotta love it. It claims to be 99% effective, but what most of us don't realize is that those numbers are under perfect conditions - you take the pill at exactly the same time every day, never miss a day, are not taking any other medications or supplements, and have been doing this for about 3 months before you start having sex.
It's enough to drive a woman crazy. Your best bet is to take the pill and use a condom anyway.:(
Whether or not he chooses to step up - which you have no control over - you have to be honest with him and let him know that he's the father. Ask him what role he plans to take in the pregnancy, delivery, and caring for your child. It won't do any good to accuse him, yell at him, or insult him if he says no. That is his choice. Yes, it is his responsibility, but you can't force someone else to be responsible.
Do you want to keep your baby?
I don't know how far along you are, but you also have the option of terminating the pregnancy. I'm not advocating one course of action or the other. Choosing to terminate a pregnancy is a VERY personal and emotional choice. Adoption is another option. There are many loving families out there who desperately want a child and can't have one.
If you do want to keep you baby, and I tell all women this. When you choose to bring a child into this world, you can hope for help and support from others, but ultimately it is your responsibility to care for that child or find someone who will.
Having said that, nothing teaches unconditional love and acceptance more than caring for a new born child. When my daughters were infants, I was grateful for every moment that I got to spend with them because I knew those times would not last long - yes, even when I had to sit up all night rocking them. Those are some of the most precious memories of my life.
You have some tough decisions to make, but only you can make them.