Allah will not impose blame upon you for what is meaningless in your oaths, but He will impose blame upon you for [breaking] what you intended of oaths. So its expiation is the feeding of ten needy people from the average of that which you feed your [own] families or clothing them or the freeing of a slave. But whoever cannot find [or afford it] - then a fast of three days [is required]. That is the expiation for oaths when you have sworn. But guard your oaths. Thus does Allah make clear to you His verses that you may be grateful. (Al-Ma'idah 5:89)
It's accepted to break an oath if you made one out of anger, or something unintentional. But the person breaking the oath must feed ten needy people, clothe them, or free a slave. If he cannot afford that, then he should fast for three days.
I could find nothing saying that the marriage would be invalid, but breaking an oath without paying the 'fine' would be a sin.