i allow him to use contraceptives because we were abstaining from sex for months
Perhaps you should focus more on this apparently innocent statement in which you rationalize the use of contraceptives in your relationship. This is an important clue on what is wrong in the whole situation.
You see, the Church teaches that there are no “private” sins, in a sense that every sin that a person commits affects the sanctity of the whole church. It also teaches that when someone transgresses against any of God commandments, it is as if the person were transgressing against all of the commandments. Therefore, even when you commit a sin that somehow might be considered “less” grave (ex: using contraception versus watching porn) you can rest assured that to the eyes of God you are a sinner no matter how serious you think a sin is.
Why I am saying all that?
Well, let me give you a different perspective on your situation: your husband watching porn and you allowing him to use contraceptives are both equal violations of the law of God. Same commandment, same intention, same grave matter.
Can you see it now? By allowing him to use contraceptives you are actually pushing him towards sin!
There is no way you are going to lead out your husband to sanctity if you don’t approach the problem of your own sanctity. How can you show him that sex is to be sanctified as any other thing in your life, if you yourself is not treating sex it as if it were holy?
The first step here is realizing what this situation is really about: it is about getting the help of God to overcome your marriage issues, and His grace has to come into your relationship through a door… and that door is your faith, your repentance, and your true conversion to the Lord.
Look for a priest and confess your sins first. Take the first step and clean your soul, then get your husband to do the same. There is no other way out of this situation. You both have to straighten your relationship with God before you even try to straighten your own relationship.
God is the only true source of love in the universe. You cannot love your husband properly unless you love God first. If you love God first, then He will give you all the grace you need to overcome any situation in your marriage. Trust, and you will see.
God bless you, your husband, and all your family.