She didn’t use a condom!

Communication is key to survival or a relationship. Ask your wife if she was faking it as part of role play. However, you should be worried and should do something about it.
In every consensual D/s relationships there are rules and limits agreed to ahead of time. If he is not respecting those and more important, if your wife is not respecting and enforcing those, its time to end the relationship – either with the bull or the wife.
First, ask you wife for the non-play version. Then have as serious talk.
Second, point out to her the rules you have and:
a) if she gets knocked up by the bull you will sue him for child support, child care and mental anguish.
b) you might divorce her and use DNA testing and her getting knocked up against your rules as cause.
c) if she got an STD from him you will report him to the CDC. People have been prosecuted for knowingly passing HIV.
Third, point out to her that if they are fucking 3 times a year he is likely fucking others. She needs to get tested for STD because she just fucked a whole chain of people. Are you having sex with your wife? You need to get tested too. (you should anyway).
There is a certain cultural bias to not use condoms which results in higher STD rates among certain demographics. I’ll let you research that one but CDC has some statistics worth checking if you have a racial, nationality or cultural side to your kink.
And no, Herpes is not harmless. There is evidence that like Papiloma virus, it might contribute to increased rates of cancer. Yes, it is only “some evidence” and “might”.
And, yes, you are dealing with the ugly side of sexual kink but now is the time to make a stand, and hope you got lucky.

What are you worried about? Pregnancy? Condoms fail all the time. STD ? Condoms fail all the time.

We both love it when her Bulls cum in her pussy. Its a requirement that the Bulls show us regular STD Blood tests and we both get tested regularly.

Sex outside of strict monogamy is a very risky business. Is it worth the risk to you and your wife? Is it worth your life?

For us, yes it is! We love the Cuck lifestyle and the risk that comes with it.
Maybe your wife enjoys him cumming in her you should be talking and sharing everything between you.
This lifestyle has the power to open all barriers to communication and increase your intimacy to levels never reached by vanilla couples.

On their 3rd date night he arrived at 7pm and I sat on the couch across the living room from them as they chatted and sipped wine as usual. She invited him to our bed and I followed as usual but he asked me to leave the bedroom ( I had witnessed the first two times but always off the bed and I stayed dressed). I did as told but stayed outside and listened in thru the opening in the partially closed door. He told her how much her adored her and had been tested for STD’s a few days prior and he showed her the paperwork verifying all clear. I could see him lightly caressing her neck and chest while she was processing this. After a few minutes she moved her hand to the back of his neck pulling his face to hers. They kissed passionately longer than I could ever recall…and then she spoke’ “I have been wanting to feel your cock deep inside me and filling me up ever since the first time. It’s just my husband and I agreed you would need to use a condom. But I want to feel you so bad right now I’m conflicted…” There was a moment of silence between them; my heart was beating so fast and strong I was afraid they would hear it! I was also so conflicted because the thought of it was so intense. Another man had never cum inside her. I had to walk away and pour myself a drink and sat in the living room waiting. And waiting. After about and hour I heard the bedroom door open. My wife came out naked aside from her belly ring, covered in sweat, flushed skin. I could almost see the heat rising off of her skin. Without saying a word she stood in front of me while I sat on the couch and she parted her legs. Slowly at first I saw thick white fluid start to leak down her inner thigh. She took my hand and placed it over her crotch. Instantly she let loose and my hand was covered with his cum and her juices. Aside from the hot goo I was holding I was overwhelmed by their mixed musky smell. Without thinking I brought my hand to my mouth and licked it. She smiled, leaned over to kiss me and said, “Thank you for not being mad baby. He had clean testing a few days ago and I couldn’t resist. It feels so good I want more if that’s ok?” At a loss for words I could only nod ok and she went back with him for another few hours with the door shut completely. I was tempted to peek in but felt I should give them private time. Around 1am I awoke to hear them talking and kissing by the front door and then I heard his car start and drive away. She(now in panties and his T-shirt)came to me and took my sticky hand to invite me to bed. The sheets were all over the place and cum stains were all over them. She was exhausted and sore down there so we spooned and drifted to sleep. The next morning she told me if we were to continue with him she wanted to go bare and be filled up. I agreed. I was able to witness most times. Eventually he moved away but we still have pillow talk about that date night.