Does the wife inherit all and how can I recover my losses?

If he had no children and no will his wife inherits everything. Paying those obligations for your brother may be considered gifts. If you consider them debts and are able to prove satisfactorily to a court, you may be able to open an estate as a creditor and obtain payment through the estate.

Your brother's Will would control the distribution of his assets. If there is no Will then his assets are distributed to his spouse. Even with a Will the spouse has renunciation rights and is entitled to 1/3 of his assets. Any assets held in joint tenancy with the spouse will transfer outside of his estate to the surviving joint tenant. If you are able to establish that what you did for your brother was not a gift but that your brother promised to repay you then you could file a claim against the assets in your brother's estate. If you can establish a claim as a creditor your would be repaid before estate assets are distributed to the spouse. You should discuss the possibility of filing a claim with an attorney.