All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is not permissible for your husband to force you to have an abortion and you should not have obeyed him in this case because aborting the sperm is Islamically forbidden. The obedience of the husband is obligatory only in what is permissible.
Now you should sincerely repent and seek Allah's forgiveness and perform good deeds as much as possible.
You should not commit this sin ever again and not seek the pleasure of any creature in what causes the Wrath of Allah.
Allah knows best.