Sorry to read of your less than pleasant encounter.
so many questions but I will share my thoughts based on what you have provided.
many times new couples and singles start off with a less then enjoyable experience. This is based on many variables but can be boiled down to one over all concentration….expectations.
the second thing that comes to mind is communication. Largely between you and your husband but also who you choose to be with. The parameters of what you want and are willing to experience. Safe words. Deal killer situations etc.
lastly there is the first time issue. Men and women are very distinctly different in this area. Generally the female gender is made to accept different and repeated couplings. As human mammals over the maturing eons of time women have choice and societal norms that restrict the natural ability with acceptable behavior norms, guilt and conscience. Males are essentially a one and done gender. Males require a refractory period of time. There is also a primitive drive to over achieve, out perform the other male. We are also very visual. We see so we get turned on. So your husband experienced what many males experience the first time or for several times, sensory over load. He saw too much, had too much happening around him, to him, while trying to keep and eye on you, protect you, make sure you were not being hurt or uncomfortable. This is why the first few experiences the male partner doesn’t achieve orgasm let alone an erection.
so my two cents is he is embarrassed and feeling left out and less than after the experience. Because of his experience and lack of he watched you move on through your experience seemingly with out issue. So he feels less than. He probably thinks you feel and look upon him as less than. Emasculated in your eyes. Very bruised ego.
do not discuss or venture any more in the lifestyle until you both are settled and comfortable with each other. If you do decide to move forward go with baby steps. Be that couple that attends, talks, mingles meet and listen to other couples but only play as a couple between you two. First in closed room. Maybe later in open room. If you want to try MFM again wait and find a single male or husband allowed to play alone that you are comfortable with and that has many years experience.
well that in general is my two cents based on what you wrote I hope it is helpful.