Is the Islamic marriage contract, which was conducted in accordance with the Hanafi school of thought, with the presence of four witnesses and a representative (wakeel), considered invalid due to the parents' lack of knowledge, and is it permissible to continue this relationship, taking into account the mentioned circumstances of the husband's harshness and financial instability?

The preponderant opinion is that marriage without a guardian (wali) is invalid, unless a Shariah judge rules it to be valid. If it is invalid, then it must be annulled or divorced. If it is valid and reconciliation is not possible, then you may seek a divorce. If he does not respond, then refer the matter to a Shariah judge. If he has consummated the marriage with you, then you are entitled to the full mahr (dowry).