Have taken over as boss of an electronics firm and have slept with an employee...?

Have replaced the last manager of an elec firm. I'm 56 and was introduced to all my employees. One of them is a gorgeous 26 year old brunette with a great body called Leeann who has just split up with her boyfriend. I sat with everyone to tell them what I expected but when I got to her we flirted and I put my hand on her leg and said "i want to get to know you a lot more better." She squeezed my hand and last night i took her to dinner. We kissed and I ended up sleeping with her in a hotel. Sex was great, she looked fantastic naked and i managed to keep up with her. But I got to the point where at the end I was out of breath and was sweating all over her. Dont want to do that again as she wasnt happy. Would viagra help