All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
We thank Allaah Almighty for your safety. We ask Allaah, the Exalted, for welfare for us and you. You have to know that whatever happens to the Muslim is good for him if he shows patience and thanks Allaah Almighty. It was authentically narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: "Wonderful is the affair of the believer, for there is good in every affair of his. This is not the case of anyone but the believer. If he has an occasion to feel delight, he thanks (Allaah Almighty), thus, there is good for him in it, and if he suffers affliction, he patiently endures, which is good for him.” [Muslim]
Concerning your question, you should fulfill your vow in the manner in which you took your vow. Allaah Almighty commanded the fulfillment of vows, as He says (what means): {Then let them end their untidiness and fulfill their vows.} [Quran 22: 29] He also praised the righteous people of Paradise because they used to fulfill their vows to Allaah, the Exalted, in the life of this world, as He says (what means): {They [are those who] fulfill [their] vows and fear a Day whose evil will be widespread.} [Quran 76: 7]
Moreover, the Prophet, sallallaahu ‘alayhi wa sallam, said: “If one vows to obey Allaah Almighty, he should obey Him…” [Al-Bukhari and Muslim]
Thus, you should not withdraw your vow or offer an expiation for breaking your oath instead of fulfilling it because it is affordable, being just a percentage of the profit.
By fulfilling your vow, you combine between obeying Allaah Almighty, benefiting His slaves, and satisfying the needs of the poor, so you obtain more blessings and rewards.
Allaah Knows best.