Yep. I usually come down harder on snooping in your partner’s private communications, but when they are blatantly and obviously lying about infidelity AND continuing to have unprotected sex with you (as evidenced by the two closely-spaced children), it is a very rarely necessary/justified act of self-preservation.

(I have done it ONCE, and I’m 43 — I think it’s a breakup-worthy offense, but in that specific case, I had to confirm that I was being lied-to and put at physical risk, the evidence confirmed it, and the relationship ended. Loss of trust is the death knell for a marriage/partnership, where I’m concerned.)