Oh no, I hope you're not considering the word that rhymes with "Shmismortion"!!! My father didn't want either of us (me or my brother) he even kicked my moms 7 month pregnant belly to try kill my brother!!! He almost forced her into aborting me too...but she hung in there. she raised two fine kids for 23 years by herself with no help from family AT ALL. But it all depends on the mother AND her belief (both in yourself and family... religion...eh).
My mom was 17 when she had me and 19-20 when she had my brother. You're 20. But just REALLY think about it. Maybe he will change his mind about it maybe not. If he is abusive then I would go with plan "A", but seriously, if you have support from BOTH families, then I don't see why you wouldn't go on with it....it's life girl!!! If you REALLY don't think you're ready and it will change your life for the worse, then don't go thru with it.