You can appear on tinder when you're not active
I think on all this dating apps, the more recently you've been on the more you show up to other viewers. At least on PoF, this can be seen because when you're frequently active you get a lot more msgs etc.
I don't know if this bloke is willing or capable to cope with someone as wounded as I am
Don't blame yourself for him trying to cheat, or for your gut feeling. I don't think there's anything wrong with you that you feel a probable cheater has been cheating. At the very least, as you've said, he was trying to chat to/meet other women months after you thought you'd both stopped that.
I've just shown a huge vulnerable side of myself and if that's too much for him to discuss and understand then I'm better off without him,no disrespect to him, he's perfectly entitled to say it's too much of a responsibility
You haven't done anything a lot of us wouldn't OP, or responded any way that a lot of us wouldn't.
As far as I know, I haven't been cheated on much in relationships, but I would still mistrust someone whose Tinder turned up so readily, or was trying to meet someone after I thought we were exclusive.