Watching pornographic websites and sexual activity is haraam; it is a disease, not a remedy. The one who does that is afflicted and he should seek to remedy himself by repenting and giving it up, not by making up excuses for himself. All sinners make up excuses for themselves. The one who drinks alcohol or takes drugs or commits adultery – they all claim that they are under pressure and that they cannot escape it except by doing something haraam.
In fact these haraam things only add to their worries and stress. One of the punishments of sin is feelings of stress and alienation, and darkness on the face and in the heart. The further away a person is from his Lord and the more he is indulging in sins, the further away the means of attaining happiness and peace of mind are from him, as Allah, may He be exalted, says (interpretation of the meaning):
“But whosoever turns away from My Reminder (i.e. neither believes in this Quran nor acts on its orders, etc.) verily, for him is a life of hardship”
As for the people of faith and obedience, Allah, may He be exalted, says concerning them (interpretation of the meaning):
“Whoever works righteousness, whether male or female, while he (or she) is a true believer (of Islamic Monotheism) verily, to him We will give a good life (in this world with respect, contentment and lawful provision), and We shall pay them certainly a reward in proportion to the best of what they used to do (i.e. Paradise in the Hereafter)”
What you have to do is advise your husband to keep away from these haraam things, and tell him about beneficial remedies to treat stress and anxiety, one of the greatest of which is reading the Holy Qur’aan, which is the means of bringing relief and peace to the heart. See the answer to question no. 21677 and 30901.
Perhaps you can also refer to the essay on “Dealing with worries and stress” on this website.
It is permissible for the husband to enjoy his wife however he wants, so long as he avoids intercourse at the time of menses and in the anus.
There are different way of enjoying intimacy that are not forbidden in Islam, but they are off-putting to people of good taste and sound natures; however they are permissible if the wife agrees to them.
If your husband calls you to do something haraam, you have to refuse and not be a party to sin and disobedience. If he calls you to do something permissible that you find off-putting and distasteful, then it is up to you whether you accept or refuse. If you decide to go along with it because you are afraid he will lose interest in you, you may do so, but it is better for you to fulfil his desires in proper ways that do not make either of you feel put off.
And Allah knows best.