Einsteins first wife, Mileva Marić, was a physicist (they met as students), but the hypothesis suggesting she had significant part in creating the theories attributed to Albert is speculation without any substantial evidence. She never claimed any credit.

She could theoretically have helped with special relativity, but their marriage became strained and they were separated at the time he developed general relativity, which is considered the greater accomplishment.

The most important evidence for the hypothesis is that Albert let her have the Nobel price money, but that was most likely not an admission of her part in creating it, but rather his way of paying for the divorce. (By the way, the Nobel price was awarded for the photoelectric effect, not the theory of relativity.)

No one knows neither Milevas or Alberts IQ. To my knowledge no IQ tests are known to exist for either. Everything you see about Einsteins IQ is "estimations", in other words pure guesswork. No doubt she was very smart, but then again Einstein was Einstein.

Source: Einstein by Walter Isaacson