You kind of already did, did you not?

You fear your sister's wrath and hate if you accept Abigail, but you fear far more what might happen if you break your sworn word to her. The word of a god is utterly sacrosanct, none of your brothers or sisters has, so far as you are aware, EVER actually gone back on something that they actually promised to do. Oh sure, they will twist the intent of their words into a pretzel, and hedge around subjects when they are speaking like a lawyer sworn to Togos faith, but they DO NOT speak Lies of Commission, not even Togos, who is the GOD of Deception.
(Then again, he doesn't HAVE to outright Lie, he just tells the truth in a way that makes you think something ELSE: as do all master deceivers.)

You don't know what would happen if you broke this absolute taboo, perhaps Those-That-Reign-Beyond would revoke your godhood, turning you into just a 0th level morphworm, perhaps your siblings would unite against you and rend you asunder, permanently de-rezing you, perhaps they would declare a jihad against your followers and erase the modest but crucial gains you have made today... Again, you don't know, but you DON'T want to find out.

Conflict resolved the silence begins to lengthen, you should find something to say...