Can we move on from this?

TL;DR

I’m 21 and in my first relationship. My boyfriend (25) often talks about his ex, says that a man can only fully give his heart once. He also said he wouldn’t feel pain if we broke up. I’ve been crying for days and don’t know how to move forward, even though I want to stay in the relationship.

I am in need of serious help, because I just don’t know what to do with myself anymore. To cut right to the chase. I (F21) have been with my first ever boyfriend (M25) for about a year now. He had a gf before me, from age 16 till 20 and they were each other’s first love.

I have always been very (retroactive) jealous about their relationship. When I first met my boyfriend trough mutuals, the first thing I learned about him was the relationship he had with his ex and how she absolutely broke his heart, and how he has never been the same ever since, and he’s got so much trauma from her. How he loved her so much and they were each others firsts with everything. Mind you, he’s my first everything. Including intimacy wise.

I ended up asking a lot of questions about her, and their relationship. In hindsight this was very stupid and damaging to do to myself. But he also used to tell me a lot of info about her (them) randomly, because he’s a very open person and he felt that he could share those things with me. He told me detailed things about their sex live. For example: He told me that he knows when she is giving her new boyfriend a blowjob, she’s thinking about him. Who even says that??

And he told me that she is still in his heart. He will later on say that he just meant that she was a big part of his life but imo you just don’t say that to your current partner that you love.

It’s things like this that he’ll say that I just can’t stop thinking about.

Now the current problem:

We had a conversation in which I asked him, just hypothetically, would you be heartbroken or would you be upset or experience pain if we broke up? And he told me, no. He said that he would think it’s a shame that we broke up, but he wouldn’t experience any pain or heartbreak. And this really, really upset me because I just don’t think it’s healthy or normal to be in a relationship with someone if you don’t really care if y’all break up. That, along with the fact that his ex also broke up with him, and it destroyed him for years.

He’s a very blunt and straight-up person, so when he told me this, it really broke my heart. That’s because I know that it would really hurt me if we broke up, and we’ve been together for almost a year now. We plan to get married very soon. He tells me he loves me every single day and he wants me to be his wife (we’re religious), I just don’t understand how you could say this to someone if you love them so much.

When we had a conversation about this, he said that he gets that it’s hard for me to hear that, but that it’s toxic of me that I would want him to have pain or heartbreak after the relationship ends, because I shouldn’t want that for him. And also, he just keeps telling me that I should stop making myself upset with these hypothetical questions, because they are just hypothetical. And he says, we’re not going to break up anyway, so what does it matter how I would feel after the breakup.

Afterwards, I asked him some more context about this, and then he told me that a man can only fall in love once in his life. Then he corrected himself and said, no, actually, a man can only really truly surrender himself and give his heart fully to a woman one time, and after that, he can’t really do that anymore. Basically saying that he already did that with his ex, and therefore, he can’t do that with me right now. And this absolutely destroyed me, because I’ve always felt like I didn’t get his full heart, because she has it, and even though they have been broken up for four years, this kind of shows me that he is still living in the past, and he is still letting his relationship with his ex determine our relationship. And he keeps telling me that I keep bringing up the past, and that I keep bringing up his relationships, and he feels like he’s being punished for his past, but the way I see it, he is bringing his relationship into this relationship by saying things like that. And I don’t know if I want to be with someone that cannot just love me with a clean slate, but that has to love me in comparison to his first love.

However, I do think that I want to continue to be in this relationship, but I just don’t know how to move forward from this. I have been crying for days and days on end, and I keep thinking and reminiscing about the things that he said, along with things that he prior told me about the relationship, and I just cannot function anymore. If there’s anyone that could help me with this, I would love some advice on the situation, and some advice for me as to what to do to move on.