Yes, you can be charged with "indecent exposure" inside your home if others are present to be offended or annoyed. Mere exposure can constitute such if "willful" and "lewd." What is "lewd" will depend on the facts.
If you are being charged with a crime you need to remain silent, that means do not discuss this matter with ANYONE other than your attorney, and includes NOT posting anymore facts here on this public forum, you have already said too much. Rather than explain what happened on this site, you should go meet with a few criminal defense attorneys and hire the one you feel most comfortable with to handle your case. Most, including those in my office offer free initial consultations. It sounds like you have pretty solid defenses based on what you have said here, but an attorney can never say without discussing all the facts with you.
If you cannot afford a private attorney (and you will never know until you go meet with some to see what they charge), you should request a public defender at your first court date. Again, DO NOT DISCUSS THIS MATTER WITH ANYONE OTHER THAN YOUR ATTORNEY, especially law enforcement.
Michel & Associates, PC
All my comments here are intended for general legal purposes. None of my comments here establish an attorney-client relationship with anyone. None of my comments should be relied on in taking legal action without first consulting an attorney.
Under Penal Code 314, it covers situations where a person "willfully and lewdly" exposes themselves in any public place or in "any place where there are present other persons to be offended or annoyed".
Several issues from your question...
Can they prove it was done willfully and lewdly? That is, deliberately and with an intent to draw attention to your genitalia?
Next - Would her testimony, without further evidence, be enough to convince a jury beyond a reasonable doubt?
You're facing allegations that if proven could land you on the sex offender list for life. Time for a lawyer.
The above answer is for general information only and is based on the information you posted. Every case is fact dependent, so to get a thorough analysis of your situation, you will need to consult face to face with an attorney licensed to practice in the jurisdiction where the incident took place. Do not conclusively rely on any information posted online when deciding what to do about your case.