Before you do anything that can't be undone, you should sit down and have a long talk about this, preferably with someone like a therapist who can help you work through your emotions around this situation.
Also, as others have said, you need to see an appropriate physician also, not just for the unborn child, but for yourself. A pregnancy may or may not be advisable all depending on your own physican health.
As you know, the pregnancy might not be viable. However, it might be.
You've said how your boyfriend feels about it--but how do you feel about it??????