Husband lies about intensity of relationship with his sister

[Onewayrelationship]

Well I've been married to the same person for several years my husband is 11 years older than myself and I met him when I was 17. We dated several months before I even met his family.  

Upon meeting his sister she automatically did not like me and did not say one word to me the entire 30 minutes I was at her home.  She did not even look at me! Well that was several years ago and not much has changed.  She could not even warm up to me after my husband and me had a daughter.  His sister has never tried to have a relationship with our daughter either!  

Well I became suspicious about some of my husbands behavior with my daughter and me not just me  he seemed uptight preoccupied  and had never had a good relationship with our daughter. Despite my effort to help him .. Anyway I decided to look at phone records and was able to go back 18 months.  I quickly realized my husband had been lying to me about how often he speaks to his sister. For example I would frequently ask how she was and he would tell me he hadn't spoke to her and that she acted distant toward him and he didn't really know how she was.

If he did admit to talking with her he would say they only spoke for a couple minutes.  I found out through phone records that he speaks to her on the phone every single day 2-3 times a day and they text each other back and forth up to 30 times a day even if they have already spoke on the phone!!  I always knew his sister was clingy and needy and seemed infatuated with him  she would kiss him on the mouth and rub her fingers through his hair!!  

Well even when we got married she was distant towards me and on our wedding day I turned and saw her holding his chin and gave him a paused kiss on the mouth!! The photographer captured the moment on film! Wow it was like who's the bride me or her!!  

As our daughter got older she picked up on things too and I never spoke about anything being inappropriate in front of her!  She started asking questions about the two of them  anyway  I was so angry he was lying to me about the frequency of his calls and text to his sister!! But why?!  It leads me to believe they have always been romantically involved  the whole duration of this marriage!!

  My sister in law is the other woman!! I've suspected my husband was cheating in the past but hell this one would be to x rated for even jerry springer!!  My problem is that my husband is very very jealous  we have been married a lot of years so how do I end my marriage based on a gut feeling of what I feel is going on and then the phone records proves he has continuously lied!!

I've never lived by myself but also my husband has stated he would "hurt" himself if I ever leave him and 3 months ago he came right out and said he would shoot himself in the head if I leave him!  That was a blow because a close relative did commit suicide via a gun in recent months!  He later said it was just a figure of speech! Wtf!  I honestly know I need to leave but how?