Need Relationship Advice

So I’ve been with this guy for 3 years now and within those 3 years we split in 2019 & 2021 and during the spit we saw other people and then eventually decided to get back together but the difference between the 2 is I got pregnant by someone else when we split the 2nd time and prior to that our sex life went to shit after the 1st dude due to him honestly being better at it and we’ve been trying to fix our sex life I literally tried everything from detoxing down there to eating right EVERYTHING and still NOTHINGS working and it’s like ion know what to do at this point because honestly I feel really disgusting with myself about the 2 incidents and I don’t think he really understands what I’m going through considering being pregnant doesn’t help cuz it’s bringing my self confidence hella low and I just don’t feel comfortable and it’s like I wanna have sex but it’s like every time we do I don’t feel him like it’s not pleasurable anymore and also before all this we talked about getting married and now we’re engaged and it’s like I really don’t know if we’re going to work because I’m literally trying and nothings ever good enough it feel like and I’m also scared of being alone considering ive been with him for 3 years so I don’t know how to be alone mind you I’m 20 he’s 37 so I’m just lost! Should I leave?