So happy for you! How often is she with her lovers? And who knows about this lifestyle you guys are now living???
I would say you need to ask her what she hopes for and what she expects when you watch her with another man? Make sure she isnt put off by you being there. And reassure her of your feelings for her, before, and after the event. And during the event you may feel like you are irrelevant, but you just have to get used to that, and get used to doing what They want of you, if and whenever they desire. Have the conversation with her beforehand. Dont wait til after and talk about what you would have liked. Make that first time with them perfect for your girl, perfect for him, and enjoyable for you. Accepting your role is key, and finding excitement in that role THEY have given you. You and her can become so close if all this is done right. And be open minded, she may start thinking of You very differently and more like a girlfriend than a man. Every cuckold couple are different. So i wish you well and enjoy the new feelings and flavours of your submissive sex life