How is it helpful to the OP to be talking about "heartbeats" and other nonsensical and totally irrelevant information about fetuses? Ughh!

Women have every right to terminate a pregnancy; it is their body and their decision alone. OP, please don't listen to anyone (or anything) that tries to convince you otherwise

Honestly I think it will depend on if you feel you can live with hiding something like this from your BF indefinitely. If it was me, I would have to tell him, because I can't live with hiding information from my significant other; she is my bastion of support due to the fact that I don't have to hide anything from her.

On the other hand you could test your relationship and see if this is someone that is truly compatible with you by telling him; if he is unable or unwilling to respect the choice you make that you feel is best for you, it might be worth reconsidering him as a boyfriend.