@Britsmums11
It is not the strength of your marriage that is in question, but the strength of his character that is in question.
It is most likely that at least on 1 day in the past that he professed his love and commitment to his first child and even to his ex. Clearly, none of those feelings stood the test of time.
Please do not lull yourself in to thinking that your situation will necessarily prove to be better or longer lasting because you are a better wife or that he is more committed to your child and your relationship. He still brings the same character that be brought to his prior relationship.
If he were to work 2 jobs, it would allow him to pay his child maintenance and contribute to the cost of the minding fee for your child.
As previously stated, many men work 2_jobs to support their families. If he feels the need to have multiple children, why would he not feel the need to get multiple jobs?
As a point of disclosure, my thoughts would be exactly the same about a female who while not being able to support her child was opting to be a SAHM.
Is your spouse modeling behavior that you one day hope to see your child embrace?