Because you were together for part of the year, the software needs some information to determine if you may be eligible for the spousal credit. If, for the part of the year you were together, your ex' income was greater than the threshold that allows you to claim this credit, then the other consideration is if you think his income would be greater or less than your income...this would affect which of you claims the UCCB. If you believe his income was greater than yours, then just enter an amount greater than your income. If his income was less than yours, but great enough to negate the spousal credit, enter perhaps $20,000. As to the SIN, if you know this, enter it...or enter 000 000 000. Beyond this, his income does not affect you...child tax benefits will be based solely on your own net income, not combined with his as in the past.
Have you also informed CRA of the change in marital status? You should do so, as your child tax benefits would have increased as of that date, again as from that date they would be based solely on your own 2014 net income, and not the combined net income. If you haven't, here is a link to the form to use...
http://www.cra-arc.gc.ca/E/pbg/tf/rc65/README.html