Should I tell him about the abortion?

It's simple game theory, really. If you've already decided to abort, then your options are

a) Tell him, he wants it - unsatisfactory outcome
b) Tell him, he doesn't want it - neutral outcome
c) Don't tell him, he wants it - neutral outcome
d) Don't tell him, he doesn't want it - best outcome

Whether he has a "right" to know or not, who is it serving to tell him if you are just going to terminate anyway?

So that he can be properly accountable for the fact that he has unintentionally conceived a child—not merely to the OP, but to his own conscience. Legality aside, the propriety of such terminations from a standpoint of moral philosophy is anything but cut-and-dried, and if he subscribes to the view that any infant however young is prima facie 'a person' then he ought to have the opportunity to come to terms with the (perhaps, deservedly harrowing) implications of such an apparently lackadaisical attitude towards physically intimate relationships.

No, it isn't convenient for the OP: but since we know nothing of their circumstances save that he ended their relationship—as anyone is entitled to do without prejudice, providing they've conducted themselves truthfully—her convenience doesn't override his right to know; if only to realise that, yes, he ****ed up.

Of course, 'game theory' may be sound economic policy, but in a world where unfettered utility maximisation kills thousands every day I'd hesitate to endorse it quite so unreservedly unless I were truly cynical to the point of solipsism. (Which, in all fairness, maybe you are.)

It's simple game theory, really. If you've already decided to abort, then your options are

a) Tell him, he wants it - unsatisfactory outcome
b) Tell him, he doesn't want it - neutral outcome
c) Don't tell him, he wants it - neutral outcome
d) Don't tell him, he doesn't want it - best outcome

Whether he has a "right" to know or not, who is it serving to tell him if you are just going to terminate anyway?

Wow, about as unethical as you can get....

What is the benefit of telling the guy? Other than some abstract notion that he "deserves" to know.

By that logic you could argue, why should the woman be free to decide to have an abortion, other than some abstract notion that she has the right to make that decision?

Well, no you couldnt. Since denying her that right will have direct and immediate consequences on her wellbeing and future. Not telling the guy has literally no impact on him whatsoever.

C'mon people I'm waiting for some benefits here.

Do whatever you need to do for you and your life OK!

Telling him or not telling is completely up to you and only he can decide how he reacts to that or if he doesn't know he can't react.

You are not obligated to tell him but being honest might be something good or it might not be a good idea. Trust your gut instinct. Also it's better for it to come from you instead of anyone else.

All I can say is no matter what your decision he will either know about your choice or not. You can consider his feelings on the matter but it shouldn't sway your decision. You are not in a relationship with him anymore. You have to take care of yourself and what's in your best interest if that means becoming a mother in 9 months or having an abortion.

I don't know the guy but he good be a decent person.would you regret not telling him? Would he care? It depends on his personality and character.

Best of luck