Section 7. No other or greater evidence shall be required to prove the marriage of the husband and wife, or that the alleged father is the parent of the child, than may be required to prove the same facts in a civil action. In any prosecution begun under section one, both husband and wife shall be competent witnesses to testify against each other to any relevant matters, including the fact of their marriage and the parentage of the child; provided, that neither shall be compelled to give evidence incriminating himself. Proof of the desertion of the spouse or child, or of the neglect or refusal to make reasonable provision for their support and maintenance, shall be prima facie evidence that such desertion, neglect or refusal is wilful and without just cause. In no prosecution under sections one to ten, inclusive, shall any existing statute or rule of law prohibiting the disclosure of confidential communications between husband and wife apply.