Step 1:
Be with your sister to make sure she is okay and has rational support from loved ones.
Step 2:
Make sure that if she wishes to keep the baby it remains healthy, and after a hopefully successful birth rip that jemone ass brother fo child support up the 139 n'Lennox.
Step 3: Never let him near the child he is paying for, bargain for this in court. He is a scumbag apparently, right?
Step 4: Once the child turns 18/21 and no longer can be claimed for support, beat his lily ass to a pulp fiction 2.