In every case of a judicial separation under this Act, the wife shall, whilst so separated, be considered as an unmarried woman for the purposes of contract, and wrongs and injuries, and suing and being sued in any civil proceedings; and her husband shall not be liable in respect of any contact, act or costs entered into, done, omitted or incurred by her during the separation:

   Provided that where, upon any such judicial separation, alimony has been decreed or ordered to be paid to the wife, and the same is not duly paid by the husband, he shall be liable for necessaries supplied for her use:

   Provided also that nothing shall prevent the wife from joining, at any time during such separation, in the exercise of any joint power given to herself and her husband.