I’m not sure it’s true they can’t be monitered. I know people with iphones who have restrictions on their internet. I never tried to block websites on my ipad but I’m sure it’s possible. Whether you should be mashgiach on him is not the question. If it’s a matter of trust or of doing things without his consent, you have bigger problems.
I find it a lot more concerning that you can’t get it worked out between you guys and instead you’re venting about your beloved husband to the CR expecting strangers to come to your aid.