If someone was honest enough to tell you about how they used to cheat alot.
Claim it was years ago, they are not the same person anymore. That they had not cheated in their last relationship which was a few years long.
Would this still bother you?
I have a history of being cheated on. I normally am a very accepting and non-judgmental person. I dont want to judge someone for their past.
But it does bother me a bit.
Am I being to harsh to want to back out on someone for this?
This person
Scorpio Rising
Scorpio Sun
Virgo Moon
Scorpio Mercury
Scorpio Venus
Sag mars
I have had someone in the past open up about their past of cheating before and I was accepting and understanding. And they ended up cheating on me the worst of all my relationships. Not saying everyone is the same but it just raises some flags for me.
It would bother me but then I would think of all the heinous things I have done in my past. Cheating may not be one of them but I can rival that for sure.
People do outgrow bad behaviors. In fact, it's common. If you have evidence he's lying, I would give him the benefit of the doubt, in part because this is what I would like someone to do for me. 
Good luck!
@elsa Normally I do give benefit of the doubt. I believe people can change. But in my mind I guess cheating once or twice and learning from it is completely good. But how he emphasized ALOT bothered me. Like maybe it was a problem?
@leobra1221 it sounds like it was a problem and he knows it?
I don't know. I used to smoke three packs cigarettes a day. Minimum! It was a problem.
I have not smoked for almost thirty years and can't imagine ever lighting another cigarette.
I am not trying to talk you into to anything. If you're not comfortable, I would pay attention to that.
High five to the person for being honest. Most people won't admit to any past wrong doings.
I cheated when I was young. 20's! And, I have been cheated on. I not only did it, but know what it feels like to have it done to me.
I would rather chew off my own arm than cheat. It's just never going to happen. People do stupid things, then they learn.
I can tell you with 100% truth and clarity that I have not, will not and could not cheat on my husband. We have been together for decades. And, I was just tested (if you can believe that) a year ago. Nope. Never gonna happen.
I would leave a person before I would cheat on them.
Scorpio Sun, Venus, Mercury, Jupiter, Neptune.
It's never going to happen. I also understand sex is driven by biology. I mean, humans have urges. When we are young those hormones go wild. Not that desire dies when you are older. I can assure you it does not. We just get smarter when we are older and learn what works and what destroys. If he admitted it to you that is good.
I would be more concerned about being a Leo with a Scorpio... that does not work. I don't care what the aspects or synastry is. How do I know? Been there.
The Sag Mars... hmmm... would be a nope for me. In fact, if I were single and found 'any' Sag in a persons chart I would run for the hills. But, that is just me. Those folks cheat on me. No matter how old they are.
What house is all that Scorpio in? I would look at that too.
@soup I have been cheated on by 2 Sag's so yes that sag placement sort of throws a pause, especially in being in a mars position.
But his scorpio is in 12th house.
His mars in his 1st.
Moon in 10th
His scorpio as well as his sag maars all fall in my 7th
Moon in my 5/6th
So, I have a Scorpio sun, mercury and Saturn, in my 12th. A SAg asc, moon and venus. I have never cheated on anyone however my Leo first husband accused me of it repeatedly. Of course all his personal planets was in Leo except his moon which was Gemini . I think that if this scorpio shared something that he did so long ago that he is being honest. I made a mistake and told my first Leo husband how many lovers I had before him and I paid the price. Its sounds like you should do you both a favor and back out.
@opalina I would like to add that having lots of lovers before a committed relationship may actually decrease the likelihood of cheating for many types of people. They've satisfied their curiosity through what may possibly have been a wide variety of partners. Now they are ready to commit for the long-term!