Cheating ?

So I was at work yesterday, and at about 3 PM in the afternoon I get a Instagram message from my husband‘s ex-girlfriend, from like 15 years ago they were together but we recently saw her at a mutual friends funeral and she has since told me that she has slept with my husband one time and if they have been out to lunch multiple times. I asked her for proof she didn’t send me any text message or any kind of call logs regarding the fact that she was telling me the truth but she did send me a picture of her Google maps showing that she has supposedly been here at my house the day that she slept with him. I don’t know what to believe anymore. If there is no physical proof that he actually slept with her the way that she claims what do I do? I’m looking for real advice, not anyone to come on here and be judge mental.I’ve been with my husband for 13 years we’ve been married for two of those years. She claims this happen in May but that they have been talking to each other since December. What would you ladies do.... I will post the screenshots of her messaging him before she sent the messages to me about her sleeping with my husband, within a few seconds she was messaging me telling me that she was sleeping with him and a few seconds before that this is what she was sending him