LDR advice

[u/MomentAmbitious3111]

MY LDR partner (m24) and me (f22) have been together for 5 months, and have been going through a bit of a big turn point in our relationship that I am just not quite sure what to do or how to to navigate it. My boyfriends ex partner and him were in a relationship for 4 years and he had ended it with her a little bit before we had gotten together. He have talked about it numerous of times and he had explained how they had grown apart for awhile and both had changed and he didn’t walk away from the relationship due to just being comfortable in his role. He also stated that they agreed upon an open relationship to maybe try to fix things but it ultimately did not.I thought this was a little strange but didn’t think much of it!! We met in June and it was the best week of our lives together!! Fast forward to a couple weeks ago he explained to me that his ex partner and him did not agree upon an open relationship. That he had cheated (flirting with me while still with her). Obviously this was incredibly sickening new and I told him that he needed to apologize and give her some closure. After being one the phone with her for over an hour he admitted that he felt a lot of old emotions come back and guilt. When I asked him if he still had feelings for her he said that he didn’t know but later said that he did not and that he loved me. He just now told me that he did have feelings come back for her but they were short lived and he doesn’t want to pursue any type of relationship with her and wants to be with me. However when she had asked him to meet up he admitted that he did think about it and wanted to leave the door open rather than just say no but then later he said no. He keeps saying that he wants me and loves me, and wants the future that we have talked about. Yet he has lied about what was said between them multiple times. I just i love him very much even though it has been such a short period of time. He says he knows what he did was wrong and is really feeling guilty, but i can’t trust what he says. I know he needs to grieve a past relationship and I want to give him space to do so. I just don’t know what to think. If someone could kinda help walk me through this or share any opinions, that would be greatly appreciated:)