White powder and residues, cheating?

When I had sex with my gf after picking her up from a party, I noticed I got white residues on my t-shirt after the sex. It was also a little blood, because I know she bled a little because of stress. Her vagina also got quickly dry and moist, like it is when we have sex more than once the same night, Is it possible that the white residue is semen from a another dude?

 

Of course it is. She was prob drunk and banged some dude and since u were not there. She prob figured u would never know anyway

 

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Does she use (cancerous) talcum powder? My ex wife did before knowing of its dangers. She may still who knows. Just saying that could be it also.