My Wife Cheated on me but denies, for atleast 3 months with ex-coworker

We have been married for 16 years, we have one son 10 yrs, Recently my wife went out to a colleagues son's 1yr old party. Myself and my son stayed back at home, she had trouble getting home, I called to help her, but I found that she called a number at that time from phone on phone company web site. When she got home i asked what the number was, she completely denied she never called, and i did reverse lookup and found that guys name, When I asked about who he was she said she doesn't know, but after lot of confrontation she said it was job related and he moved to different company and she was trying for job there. but I guess it would not be on Sunday evening.
I was really mad and did more look up of the phone on previous months billing cycles, found several calls in a day at-least three to four days in a week. I started asking more questions and what, she initially started denying saying those calls went by mistake,I could agree if there were one or two calls but not for 100 calls. Later that night she broke down crying and came to be asking for mercy and forgiveness. I was shocked didn't know what to say, I asked if they had sex, she denied and said it was for attention. But she has erased every single call from call log on phone every time she made, also i caught that she was communicating on linked in(she went to one of the friends house to ask how to delete linkedin message, found out from her friend), she said she deleted all linkedin messages. But still denies having sex...when asked how long this has been going on she says since Jan until April, even though that guy was colleague for 10 years in same company. The other things I had seen was she bought expensive lingerie, acting weird, shaving private area, sometimes she used to wake up in the morning and cry. I have lost trust in her, she lied about all this as I had to dig thru to find out.
Should I believe her denial of not having sex ?
what should i do now, i am so devastated, my son has some needs and we have big house having married for 16 years, it is hard for me to digest that this is happening....my son doesn't what the house sold as he grew up there and i have been going back and forth in my mind what to do...please advise