I hear this sentence almost every week one way or another! Of course, it is a direct translation from the Spanish sentence: "Soy el culpable".
Although the translation of "culpable" is "guilty", the phrase "Soy el culpable" should be translated slightly differently. In the end, a better version would be: "It is/was my fault".
This is important because "guilty" is generally used in more formal setting such as a court of law or statement. If you are speaking to your friends or colleagues a native person is much more likely to use the phrase: "my fault".
So the correct version of the sentences in the picture and title should be:
1) It's my fault!
2) Is it your fault?
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.