"Sexually Exploring" - as a Toddler?

Hi ladies I'd like to start of by saying my toddler is a male and 3 1/2years old.. We started to notice around 1 him playing with his privates which I was told could mean it's time to potty train. So that we did, however shortly into starting potty training I ended up having to get induced and had my 2nd and being home myself 16hrs a day with a 1yr old and newborn I gave up on potty training.

Flash forward to age 2 we notice he has become self aware of the pleasure feeling of touching his private. As he's in training pants, he would touch his privates over them giving himself a baby boner. We told him it's not nice to touch our privates and it can cause ouchies as he would touch it so often he'd get sore and irrated/ rashes down there. We thought we had that stopped but then noticed he wasn't touching himself anymore but humping his stuffed animals, pillows, blankets, ect.

We then had a talk where we told him that too could give him ouchies and it's not nice to play with our toys like that. Also that pillows and blankets were for bedtime not for doing that, becuase that wasn't a nice thing to do.

Now at 3 we are seem to just throw everything mom amd dad have taught him out the window and just are back at the touching himself, humping things again. An now a new one... Putting his privates in his brother's face. I've caught him doing this 3x now each time we've had a talking, and timeout. Tonight he took his underwear off as he was to get undressed for bath time, during this time I started in on running his bath. I then walked to go get him from his room and he was telling his brother to kiss his pee pee as his privates were in his brother's face.

I know there is nothing happening with my kids and their Dad as he works 16hr shifts Monday- Saturday. An Sunday we spend the whole day together, and my partner is a bit lazy on helping with the kids when it comes to diaper changes, ect. as it's his 1 day off of work. They don't watch any adult shows at home, they watch kids cartoons. An we don't do anything sexual in front of them.

I don't get where this is coming from, I'm so frustrated because as a kid I was sexually groomed by my father. An my older sister who was groomed by her biological dad and my father, (her stepfather) would do sexual acts towards me. As a 4-6 yr old I didn't know any better and I let it happen. I now know it's wrong as a adult and it's always been something that's made me feel weird and gross as I feel like I should of know. I just remember we'd have to share baths and even when I didn't want to as she called it play with her she'd kind of force herself onto me. The same with when we'd go to bed, she'd sneak out of her bed to touch me and "eat me out." She even took it as far as blindfolded me to play "pinata" only for it to be her holding me down and letting my older cousin rape me at 4yrs old in the basement.

That's something I never wann to imagined my kids would do to each other. As there isn't anyone around them being sexual towards them or in front of them.

The only people I know who did something sexual in front of my son when he was 1 hasn't been in his life since I found out that while watching him when I worked they'd have sex, while he slept in the crib in their room. I do honestly believe and hope everyday that they'd of never done anything to him. As she was honest about having sex with her husband after my oldest fell asleep in the crib in their room.

I just don't know what to do I suppose to get my 3 1/2 year old to understand that privates aren't for other to touch or to make others touch. That privates are to potty and even if it feels good it's not nice to touch ourselves or hump our toys and bedding.

An advice would be so helpful, becuase I'm at my ends, I don't want to traumatize him when he's older. But at the the same time I don't want my youngest being traumatized as well.