Am I liable for half of the debts resulting from the loss of the project in which I participated with effort and by bringing in projects, knowing that the partnership was verbal, I was unaware of the company's previous debts, I had demanded a formal contract but it was not issued, and I only received my expenses from the project?

The rule for losses in companies is that partners bear them proportionally to their capital and assets. If two partners jointly own the capital, the loss is commensurate with each one's share of the capital. However, in a "company of faces" (where there is no capital, and the two partners buy on credit), the loss is proportional to their ownership in what they purchase. If you own half of the establishment, you bear half of the losses and debts. Each partner is an agent and guarantor for the other, and the loss is commensurate with the ownership. If a partner takes money from the project to pay off his debt, you have the right to demand it back and take that into account when calculating your share of the loss.