I'm really sorry to hear about the difficulty you and your husband are going through. It sounds like you've taken the high road by choosing to love him and prioritize your relationship, even though you disagree. Since he hasn't done this, though, I can definitely understand why it would be wearing on you.
I'm sure you and your husband have already had many conversations about this, but it might help to phrase things very directly to help him see that his attitude towards your disagreement is unfair and not in line with your attitude about it. You might say something like, "What is more important to you, me becoming an atheist or us having a happy relationship? I've chosen to love you and try to have a good relationship even though we disagree, and I'd be okay with us believing seperate things. I'm willing to let you believe what you want. But I feel as if you care more about convincing me I'm wrong than you do about the effect this is having on me. It's really wearing on me and it's breaking my heart." Try to bring it up in a non-confrontational context (ie, not in the middle of having a discussion about religion) and in an atmosphere that's conducive to having a serious, thoughtful conversation. Help him see that you're not trying to argue with him or accuse him excessively; you want his help and cooperation to improve this aspect of your relationship.
Regardless of how your husband reacts or whether his behavior improves, know that the Lord is mindful of you and wants to support both you and your husband through this trial. The covenants you made at marriage are still in effect for you, as long as you live faithfully, and the Lord can counsel you in how to best support your marriage, and to what point He expects you to endure this trial. If you haven't already, ask your bishop or home teachers for a blessing, and continue to read your scriptures, pray, attend the temple, and feel close to the Spirit.
Philippians 4:6-7 reads, "Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus." I can testify that even in circumstances where we don't even understand how peace could be possible, through the Atonement, the Lord is able to provide us with a deep sense of personal peace even when a situation doesn't seem to be improving.