Legal Question in Criminal Law in Texas

You're entitled to at least 10 days notice of any material changes to the indictment. If your trial date is soon, depending on what this conflict of interest involves (your definition of that term may not be the court's definition), you may or may not be able to get another attorney, but you'll probably be required to have a little hearing to get the issue sorted out regardless. As to how to do that, it would depend on whether you're going to retain your new attorney (in which case they'll take care of that), or you expect the court to appoint you new counsel. Assuming you want the county to pay for it, you'd just send a letter or motion to the court explaining the situation and asking that the court either appoint a new attorney or give you a hearing so that it can hear and consider whatever evidence you have as to why you think you need a new attorney. Since you're not an attorney, the court's not going to require any magic language or special format, just that you make it very clear what the problem is and what you're asking for, and that you do it soon enough that it won't delay the trial (you'd probably get a continuance anyway, but the court wouldn't be happy if it looked like you'd known about this for a while and hadn't raised it).