Do I say something, again, about suspected cheating

I don't know where to start with all this.

About 6 months ago I started to suspect my wife of having an affair with someone at her work as she was having what I felt was excessive contact with him via meetings at work, texts and calls along with other things.
I confronted her about all this and we spoke about it several times and got it all cleared up that nothing was going on.
I'll ad,it I had a little mental breakdown. At the time and the docs put me on sedatives to calm me down. I'm all better now.

My recent issue is that she had arranged to do some overtime last Saturday and the. at the end of the week changed her mind and wanted to work Sunday instead, she said it was due to the fact if she was in on Saturday shed have to deal with a miserable person at work whereas Sunday shed be on her own and could work in peace. No problem here.

However on the Sunday I was cleaning the house thinking she'd appreciate a nice clean house when she gets home when I noticed her under wear draw was open and I opened it up and looked in and it was a bit of a mess (don't ask me why I went in, I don't know). I looked and I was sure that a pair of her (sexy) French knickers were missing, I know she has 3 different pairs and I was positive one was missing but left it and thought maybe i was mistaken and she didn't have 3 pairs.
Later on that evening after she'd come home I noticed the draw a jar and opened to look in and saw the missing pair on top and at the back of the draw, so I picked them up and went downstairs and confronted her about it, she was very red faced and said she didn't know what I was talking about and that they must have been in there.
I asked if that's the truth why are you so red faced to which she replied your waving my knickers about of course I'm embarrassed and red faced.
We spoke a it more and she convinced me I was mistaken about gem being missing but I was so sure they weren't there earlier on, I thought I was going mad. I should have put my helmet cam on the wardrobe and I'd of seen if she'd put them back or not.
The night before she went in for the overtime she seemed quite turned on and was insistent that we have sex and she seemed a it more into it than normal, I now wonder if she was getting turned on knowing she was going to do something the day.

After we spoke I left it alone and dismissed it as me being wrong but now a week on she says she has itching and is sore down stairs but it's because of over cleaning as she's on her period at the moment and she also has signs of tonsillitis, looking up tonsillitis for her, a link popped up about gonorrhoea and these both seem to be signs of it, I must add that she also has a high temperature so it could be genuine illness and coincidence.

Also this evening looking at one of her legs I noticed a long thin bruise almost looking like a forefinger and she said she didn't know about it and then as she turned a it there was a wider bruise to the side of it so I put my hand there and it definatly looks like bruising from being grabbed by a mans hand and its on the rear of the leg so it looks like she has been held or grabbed quite hard, I said that's a hand mark and she just sat there quiet for awhile before saying I don't know where it's from.... I'm pretty sure it's not from me as she's on her period at the moment and we haven't been rough playing.
I'd also say from the colouring of it that its about a week old, could this be from the Sunday when I was so sure her sexy under was missing and then replaced.

Well that's the back story, my question is should I confront her about it all again and how do I go about it.
I don't want to keep questions her about these things and end up driving her to having an affair is she isn't already.

We've been married for nearly 3 years and together in total for 13 years.

When we spoke last weekend I said to her you don't have to give me any names but if something is going on tell me now and we can work through what ever problems we have but don't lie to me and let me find out later about it.
She said nothing was going on with anyone