Advice needed

Hi all. I really need advice.

If your fiancé is constantly asking who you're talking to and what your talking to them about would you feel trapped?

I lost my baby last year and after his funeral I have been stuck in really bad depression, which if I'm honest does make me consider suicide sometimes.

My fiancé is constantly talking to his ex wife, they call each other pet names and he knows what's going on in her life 24/7. Obviously this spikes up my depression even more.

They have 2 kids together and he promised me they only talk about the kids but that's not true as he's told me.

He looked through my Facebook one night when I went out for the night with my girl mates. He kicked off about the way I was talking to my best guy mate from BEFORE we got together. And threatened to end the relationship.

He then accused me of cheating on him and giving him an STI because he had a sweat rash. Which the doctors confirmed that was a sweat rash. Should I be worried he has cheated?

Feeling fed up guys :( not sure if I should talk to him, end the relationship or if I am over reacting. Please what's your opinions?