This is what I would prefer to call ‘Emotional Divorce’. Staying together, he does not bother about you and you are involved with someone else. Once you have burnt your fingers in love marriage, now make sure his friend is not taking an advantage of your disturbed marital relationship. Otherwise, you will burn your fingers again.
If you wish to improve your relationship with your in-laws then only you have to take initiative. You cannot expect them to take first move, as they are very negative about you. I understand that this is difficult but still you can try, if you wish to save your marriage.