Did you mean your life with DH are entwined or the other person ?
Regardless of if it was romantic or not , anyone who shows you attention and compassion is always worth holding onto that friendship in my book , they were your handhold through a trauma and was obviously what you needed at that time.
Of course you felt / feel anger towards your DH , they are supposed to be your handhold and support , I had a awful trauma within my own family and my DH was no where to be seen , actually said at the time and now he couldn't cope with it , i ended up seeing a counsellor weekly to support me through that time. Ive never forgiven him for his lack of support and compassion.
I supported DH with MIL dementia and subsequent death ,and SIL mental health and cancer and subsequent death , sorting funeral/house/probate ect , i wish i hadn't as it made me even more resentful for his lack of support when i needed it most.
Men do shut down with trauma , i think its quite common , we reach out and need to vent/rant/cry whatever , I guess we all deal with things differently and its a blessing you found someone to support you and be there.
Id question of your feelings for this other person is romantic ? if not do low contact if you cant go no contact , for self preservation and for the sake of your relationship
Good luck @W0nderingandWandering