Forcing my spouse back to work when we separate

You have raised two concerns. In terms of joint custody, we would need to speak with you to learn about your factual circumstances. For example, you mention that you have three children; however, you did not note their ages which is important information.
 
In terms of forcing your wife to go back to work, no you cannot. However, depending on your facts it is possible to make an argument that income should be imputed to her when calculating the child support and/or spousal support obligations. In essence, an imputation means that if, for example, you earn $50,000 per annum, and a Court imputes $50,000 per annum to her (meaning that the Court finds that she should be earning $50,000 per annum even if she is not working) then the chances of spousal support should be slim. However, of course, you should speak with a family law lawyer who can assess your unique facts in relation to the law.