My husband(M37) went to a bikini shoot without telling me(F28), he is also acting weird, please give me advice?

Me and my husband have been together for 4 years.After giving birth, my husband and I only had sex once every 6 months even when we both have high drive in sex. I have tried to initiate several times but he often said “later” or “i’m tired today” and we ended up not doing anything. I recently found out he went for a bikini photoshoot with 2 young models without letting me know and i only found out when he was editing those photos secretly. Photography isn’t his profession, he does it for fun but never taken this kind of photo before.

I asked him why he didn’t let me know and he said it might be fun to have some harmless secrets. I was really upset and feel absolutely disrespected. Recently my husband went overseas for a dental treatment, he supposed to stay with the relatives. However, 1 week after the trip, i found out he stayed at an airbnb outside, he has his reason but didn’t let me know at all until i found out myself. I feel very insecure over the fact that he kept avoiding to inform me things that could bring him so much troubles. Am i overreacting, i need advice please. What can i do to deal with this?