It is customary to trust close people, but it does not always work out. If your husband becomes suspicious and refuses to tell the truth, it's time to check him out. Thanks to modern technology, it is not so difficult to do this, it is enough to have a smartphone.
And so that you could find out about who your husband communicates with through his phone, you can install special programs https://www.virtuabroadcastnetwork.org/how-can-i-read-my-husbands-deleted-text-messages/ who will show you this. Even if the messages have been deleted, you can find out what was written there