Husband in dating/hooking up apps

Hey all, good day! I wanna ask you guys about something, i caught my husband on dating/hooking up apps recently. I dont know if i'm being over dramatic or not. I was not able to see their conversation, when confronted, he admitted that he has been doing it everytime we having argument (married for about 5 years). Our sex frequency is honestly not that high, but in my opinion, he rarely initiates too. We have a 3 year old kid. When i was pregnant, i had the placenta previa condition which prevent me from having sex with him. Our sex frequency also was not that high even before we got pregnant. When asked abt the apps, he said he just did it because he was not getting enough from me. I admit I rarely initiate the sex . So my question is, is it normal that i feel so mad and thinking about a divorce? Would you do the same?