Praise be to Allaah.
We ask Allah to forgive you and accept your repentance, because zina is a serious matter and a major sin, and having an abortion after that is another sin. We ask Allah to keep us safe and sound.
But whoever repents, Allah accepts his repentance.
We advise you to turn to Allah, may He be exalted, and to do a lot of acts of obedience and worship, in the hope that Allah will expiate your previous actions.
If the abortion took place before eighty-one days of pregnancy had passed, then the bleeding that resulted is not regarded as nifaas; rather it is irregular bleeding that does not prevent one from praying and doing tawaaf. You should have prayed during these days, and your Hajj in that case is valid; and you have to make up the prayers that you missed.
If the abortion took place after eighty-one days of pregnancy had passed, and there were signs that the foetus had begin to take shape, then the blood was nifaas, in which case prayer and tawaaf are not valid.
But for the person who lives in a faraway land and cannot wait in Makkah until she becomes pure, she may do tawaa, according to the more correct opinion. However, for the one who lives close (to Makkah) or for whom it is not difficult to come back, or who can wait until she becomes pure, then she should not do tawaaf if she is still bleeding; rather she should wait, or she should travel and come back, and her Hajj is valid, except that she remains in ihraam and does not complete the second stage of exiting ihraam until she comes back and does tawaaf.
The second stage of exiting ihram (al-tahallul al-akbar) is the stage after which it becomes permissible to have intercourse and to do the marriage contract; a marriage contract done before that stage is not valid.
For more information please see the answer to questions no. 37784, 143089, 14217 and 47289.
And Allah knows best.