If you are intending to contest the charge, I suggest you talk with a lawyer about representing you. I would expect that this is a minor enough offense that you are not looking at any real possibility of jail time, but you may find yourself being required to pay a fine plus the expense of replacing the windshield. You may also have a conviction record that you really don't want. At a minumum, I expect a lawyer can get you a 'deferred adjudication' meaning that after a probation period with no other convictions your record will be cleared. However, given the potential 'gray area' of events, if you have a witness with favorable testimony, you may be able to cast enough doubt on the events to avoid conviction altogether.
You will need to pay for the lawyer, of course, regardless of outcome. But, since this is not exactly a major case, the cost would, hopefully, be minimal.