All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
First of all, you should know that it is evil to be in contact with that young man, as he is a non-Mahram (marriageable) to you. This is an even greater sin given that you are married, as this is a disobedience to your Lord and a violation of the rights of your husband. Hence, you are obliged to repent and cut all contact with him. Please refer to fatwas 85179 and 196371.
On the other hand, that young man inciting you to separate from your husband is a kind of spoiling the relationship between you and your husband (Takhbeeb), and this is forbidden in Islam. It is an evil act which a good man would not do. It is so evil that some scholars stressed that a man who turns a wife against her husband and makes her separate from him is not allowed to marry that woman. Please refer to fatwas 17829 and 92056.
As for the need for love and sexual satisfaction, then you should try to reach a mutual understanding with your husband about this and urge him to seek treatment if he needs it. If he is cured and the problem is solved, then praise be to Allah, and if there is no change and you are harmed by this, then you have the right to ask for a divorce because of the harm. For benefit on the valid reasons for asking for a divorce, please refer to fatwa 131953.
It should be noted that the benefit is not always found in divorce.
In case divorce takes place and you wanted to marry, we advise you to not be misled by that young man. Based on his behavior, he does not seem to be suitable to be a good husband for you; how would you be safe with a man who tries to ruin a couple's marriage?
So do not be lured by his claims that he loves you; you do not know him and he does not know you, except through Facebook.
You should not accept someone as a husband except if you know from trusted people that he is pleasing in his religion and conduct. Abu Hurayrah, may Allah be pleased with him, narrated that the Prophet said, “If a man whose religion and moral conduct are pleasing to you proposes to you, then let him marry.” [At-Tirmithi]
Allah knows best.