Relationships trouble

I am in this space where I am recognizing that my thoughts that are creating my feelings.
I am aware of all of my thoughts around my boyfriend.
Some days negative thoughts are coming and going and that’s OK. Some days they are painful and fearful because I do believe them. Especially when I have some fight with my boyfriend. He criticizes me about the fact that I am not someone who takes care of things. It really make me sad.
I do believe that I have the possibility to change my thoughts but it doesn’t seem to work.
I am in this situations for months and I want to improve my relationships with him. I want to be with him. But the continually flow of negative thinking made me think that maybe I do something wrong.
Here are my negative thinking :
Does really this relation that i want ? (i often think that after he said things that i interpreted as negative)
Is someone better for me exist ?
If this negative thinking continue maybe its for something?
Is that the right guy for me

I know that sometimes when i am thinking “does really what i want ?” I feel sad devastated and confused.
When i am thinking i am with him and i can be happy with him, i love him, i can choose him, i feel so excited.

What i want in a relationships?
I want to be happy, loved, understood, connected, worthy, and I want raise children and built a family.
I truly think that i can have it with him even though he has no faith in God because I think he has same value as me.
but sometimes I feel so confused

I understand the 50/50 but now i am 80 crappy and 20 happy.

I know I am scared of the separation ….cause I want to build a relationship and have a family and kids.
Anyway if I had to choose to be with him or alone with the same happiness. I choose to be with him.

I used to have a previous relationship. A total different person, but same thought and same feelings. So I acknowledge that everything come from me.
Sometimes he is not here but I am crying because I am thinking with visual feedback of the separation of my old relation or negative future scenarios that we break up.

But now how do I shift my negative thinking belief permanently? .
Please help