Is it obligatory to fulfill a vow made while suffering from severe obsessive-compulsive disorder that affected one's will and thinking, out of fear of failing exams, knowing that the vow is burdensome?

A vow becomes binding through the act of a person who has free will; the vow of one who is coerced is not binding. Therefore, if the vows were made under the influence of obsessive thoughts to the extent that you were deprived of your free choice, then nothing is incumbent upon you. However, if they were made by your own choice, then they are binding upon you.

When considering a vow, one looks first at the intention, then at custom, and then at the wording. If you intended by the vow a success that would qualify you to enter college, then it is only binding upon you with this success.

A conditional vow is disliked, but it must be fulfilled if the desired condition for which it was made occurs, provided it was not a vow of disobedience. The mere difficulty of fulfilling the vow does not nullify it as long as you are capable of it, and expiation is not sufficient for it unless you are completely and irrevocably unable to fulfill it.

The cure for obsessive thoughts is to ignore them and not pay them any attention.