Omfg i cant believe this happened

Husband did something odd when i was out of town for the weekend...he invited a newer friend over, this friend gives off kind of a dirt bag vibe but i thought he was funny and pleasant the times i interacted with him. Lets call this guy Bob. Well today i am cleaning inbetween the couch cushions which i never do *oops* and find the top of a condom wrapper. My husband and i use condoms but not with this color wrapper. I didnt think anything of it being tied to my husband because i trust him fully when it comes to being emotionally/physically faithful to me AND we had our close married friends that stayed on our couch in april for a long weekend so i figured it was theirs. Regardless i asked my husband "have you had sex with anyone other than me on our couch?" He said no why? And i said "because i found the tip of a condom wrapper in he couch" He then says "oh.. its bobs." And im like BOB?? WHAT? HOW? he then tells me the night bob came over to hang out while i was out of town, which i knew about, bob invited a lady friend over and i guess quickly fucked her while my husband waited outside which i hadnt known about lol. Bob is married. Bob has children. Bob is a piece of shit in my eyes now. My husband said he was going to tell me when i got home a few days later but forgot (we have busy schedules.) Let me add my husband has been emotionally abused his entire life by his mother so he is extremely passive and many times gets used/walked all over or tells people what they want to hear because he and his siblings have dealt with an emotionally abusive mother. He also thinks pretty much nothing ever is a big deal because his mother makes mountains out of mole hills 24 hours a day so i believe he has learned to minimize anything to decompress stressful situations. He is very laid back pretty much all the time which sounds awesome and it can be but not in cases like this ha. So im PISSED and hes like "its not my business he can do whatever he wants with his life" and im like yes true but IN OUR HOME? and i had to find out a week later this way? He has apologized and says it was weird and wont ever happen again but i am just so astonished that this weird fucked up situation happened on the very couch im sitting on when i wasn't here. I guess i just want to know if i have a right to be royally pissed off and how to move forward?