Is it true that if there is semen on the sheets then it would be assur to make a bracha or say shema in that room?
Answer
There is no prohibition regarding saying Kriat Shema or making brachot when there is semen on the sheets. You should wash your hands after relations before saying a bracha or Shema (ideally pouring water over each hand three times, as you do when waking up in the morning).