I'd need more information to answer this question adequately. But here's a shot:
Child Support--I cannot imagine how the father could possibly sue you for "child support". If he has given you any money since learning you were pregnant, or contributed in any way to your maintenance, it seems to me that the payments were a gift, and he would not be entitled to any refund.
Costs of DNA test--If he wishes to take a DNA test to prove he's not the baby's father, again, that would be a cost he'd incur on his own, and I do not think he'd have the right to demand reimbursement from you. However, if the question of his paternity ends up in court--if you sue him for paternity, for instance--and you or the Court insists on a DNA test, AND if it turns out he is not the child's father, then he may be able to argue that you should bear the costs he incurred defending that lawsuit. HOWEVER, courts in the United States generally follow what is called "the American Rule" regarding attorney fees and litigation costs: simply put, that rule is, "you pay your own way". Be advised that courts break this rule all the time, though, and that the potential of having to pay the other side's attorney fees and costs is just one more way courts try to discourage litigation, and promote compromise and agreement.
To make a long story short, I would strongly consider consulting an attorney in Indiana before pushing the paternity issue.