Bigger/Plus size ladies on top

I am the worst. I'm decently bigger then my man and every time I try to go on top, I end up like crushing him.... Together for 3 years and I have no idea how to ride him. I have NEVER been able to. It's honestly sad 💀 we'll say I'm 250lbs atleast and he is like, maybe 200 or a little less. Another thing I find is that so much moisture happens Inbetween where my leg and vag meet, and sometimes it gets chaffed in there. Any products to use to stop that? I really hate being so intimate because I'm always just scared of stupid shit