You take it very, very slowly .... and, in my case, I raised my "standards" much higher than they were before. In other words, I always used to bend over backwards believing myself to be being "reasonable" when in fact I was being a doormat.
When I started dating again after a long time on my own when I rarely left the house, let alone dated, I dumped 2 guys in quick succession because they let me down, IMO, very rudely and inconsiderately. I know it's a cliche but when there's plenty more fish in the sea why put up with any crap ?
With that in mind, there's no reason why you shouldn't get involved, have fun, experience love again ....... yes, it is scary, because no-one likes to get hurt but what is most scary, having to kiss a few more frogs before you find your prince, or doing nothing from fear and being on your own forever more ? Only you can answer that ..... some people choose to be on their own, and are happy with that, so that's not necessarily the wrong choice. However, the fact you're already dating again sort of shows that you're probably not one of them.
So go ahead and enjoy it for what it is. Goodness knows, you deserve some love, fun and attention. Remember you can always get rid (I know that might sound a bit harsh but you are most important) as soon as he does something which makes you feel uncomfortable but you might just hit lucky and may never need to do that ! (hopefully)
Imagine if you had a crystal ball, could look 3 years in the future and see a great future with this guy ..... you'd be really mad at yourself if you'd kicked him into touch for no reason other than your own fear wouldn't you ?
Take it very, very slowly and let him earn your trust, simply by being a nice, considerate, thoughtful bloke. Believe me, I've been cheated on too, and it does kinda leave you very finely attuned to anything untoward going on. Chances are that this new guy wouldn't be able to cheat on you even if he wanted to - which I'm sure he doesn't.
Please go ahead and enjoy this ...... by taking it nice and easy and by being "vigilant" (god, that sounds a bit OTT, but you know what I mean) it's unlikely you'll get hurt.