So, he accidently text me from another phone ...

[OrangeFace]

Last night about 11.45pm I receive a text off an unknown number. I read it and it's DP (I know this because the message contained an in-joke that only me and him know. The message was obviously meant for me, and nobody else.
What is concerning me is - what's with the strange number??

He has recently changed his phone but I have both his old number and his new one. This number was totally different. I played dumb and text back saying "who is this??" and he has not replied again.

He does have form for lying, sneaking around, dating sites etc. If he can't explain this one it will be nail in the coffin for us. Am I being harsh?

Sounds like this is probably one of many things that has been foisted on the OP by this idiot.

Sounds like you are well rid OP. I very much doubt this relationship will improve. Be strong and move on. Lots of lovely Mumsnetters to support you here!

But you said the original message was with an injoke that only you and he knew about so it was not his dd texting you............

exactly, gossip...

Erm, we have already established that he's a liar and not too bright at it.

It was just that some comments seemed harsh towards the OP, not her DP. That's the difference.

I was very harsh about him.