First let me tell you that God will absolutely forgive you! His mercy, love, and forgiveness are infinite! I would encourage you to go to confession as soon as possible and lay your heart at His feet. As far as your concern’s with whether or not marital relations are a sin after a tubal ligation I would like you to visit http://www.onemoresoul.com. There is a lot of information on this subject on that site. I know you said that NFP hasn’t worked well for you, but my hubsband and I use it even though we haven’t had our reversal surgery yet to make sure that we aren’t having marital relations during a time that would otherwise be fertile. Catholic teaching is that ANY contraceptive sex is a sin, including after sterelization. Don’t panic though, there is always hope! Don’t forget that God’s love and forgiveness is infinte. I can’t tell you what you should do since every situation and relationship is unique, but I can tell you not to lose faith or hope, keep your eye’s on God’s will and He will help you through.