Is he cheating or am I being paranoid?

[Gettingthroughlife]

Hi new here hope I'm doing it right :)
Small back story:
Been with my partner 5 years
Met him online got on brilliant but he decided he wanted to get back with his ex so blocked and carried on with life
Few months later she dumped him again and he came to me
(Yes I know big red flag)
But i had never connected with someone like this before so thought why not
Partner and his ex have a child together which makes everything a bit more difficult, I love his son he is here every week 3/4 nights
But this also means partner has to meet up with his ex on a weekly basis
At first I thought nothing of it, he had moved on his ex had moved on
But then I noticed every time his ex split up with her partner the weekly change over with his son was taking longer and longer
I must have known something was going on because after 4 years of being together I decided to check his phone.
This is were I found messages of them flirting, my partner saying things like "why would I want to know about your newest fling you know how I feel about you"
And his ex saying " why you bothered you have a gf, you're only bothered because I'm not going to be your drinking buddy anymore"
Litrally tons of messages
I kicked his ass out I was so shocked I couldnt believe it
But because I'm clearly stupid I believed him when he said he doesnt want her etc
This was a year ago
Now I'm in the situation of every week he goes to hers to drop his son off im paranoid, I try not to be, I try not to let it bother me, but omg its hard!
Last night I kept seeing her name pop up on messenger when we were watching a film
After the film I just casually said "oh what did want?"
And he flipped, said he wasnt messaging her?
I said wow that was an over reaction I presumed it was over child
Then yes I got more paranoid, I said why be so defensive, can I see your phone?
He wouldn't let me ans started telling me Its never going to work if I cant trust him etc
Which I agree but he shows me in no way what so ever that I'm wanted
Everything he does I end up questioning in my head
I know I should just give up and split but we also have a child together and I do love him
Does his shifty behaviour suggest he is actually cheating? Or am I being paranoid?
Will I ever be able to trust him again?
I try and speak to him but he just says "oh your ruining the day, ffs this again" etc
I'm so lost 😫

Just get rid of him, he's clearly taking the piss out of you.

Sorry to say it but yes it does very much sound like he is cheating. And even if he isn't, the message about his feelings confirms he definitely isn't over her and would probably be with her if she hadn't dumped him.

You don't deserve what this relationship will do to your self worth, he is clearly too wrapped up in his ex to think about you and what he has.

100% you should leave.

Whether he’s cheating on you or not is totally secondary here (although I do think something inappropriate is going on). You’re second best to him; she knows that, he knows that, you know it. So why are you putting up with it?

He still loves her. Even if they aren't physically cheating that would be enough for me to end it. How can you be happy when he's still in love with someone else? The mother of his child, who he will always be tied to and see on a regular basis for years to come?

I couldn't live like that

Of course he's cheating.

He's a shagger and shaggers will shag. 🤷‍♀️