He called you ugly because he is an immature little boy. I can't comment on your weight, perhaps you are overweight, but most women and plenty of men will have stretch marks and it just is what it is. And if he found you attractive beforehand, I suspect you are not bad looking.
If it was me, I would likely not want to stay in a relationship with this individual. Relationships are about respect and accepting your partner and all their flaws as well strong points, and if your partner isn't able to do that with you, the two of them are probably not compatible...