So no backstory or anything to this really but please can someone tell me if AIBU or if, as I think, I'm being fair enough.
I'm having a small party at home soon for DC's birthday, 4-8 year olds coming if that makes a difference. I have a Ddog who is a pest with food and things so have arranged and paid for them to be looked after for the day to save me stressing and poor Ddog ending up locked away somewhere. DP, who for context doesn't live with me and has no DC or anything, has asked me if his DB's dog can come along to the party. No backstory with in-laws or anything and usually I wouldn't have a problem. This is the first time DP's DB will be coming to my home. I've said no on this occasion as I've already arranged for my dog to be looked after for the day to alleviate the stress of them running about all the kids and stealing food and stuff. Both dogs are small breeds but still I'd just rather there was no stress. DP thinks AIBU to say no and should let DB bring the dog and he's fallen out with me a bit over it. There is somewhere the dog could go so it's not preventing him coming. DP's making me feel terrible. I'm not usually one to say no to things as I hate hurting peoples feelings so I feel extra bad! Am I in the wrong? Should I just let them bring the dog? It's my DCs first proper party with their own friends and things as well because of stupid Covid so I'm working extra hard on a tight budget to make it special. It's just taking the shine off it all a bit having this to worry about. DP suggested I message DB to say the dog can't come as well which I've said I'm not comfortable with and I feel like he's trying to make me feel guilty. I don't know DB that well, only exchanged the very odd couple of sentences a couple of times. So it would be strange for me to say anything I think and make me look a bit mean. Any advice/opinions welcome!