His products can be combined with A, B, C and D, and your invention can be combined with E, which depends on the difference between your E and its ABCD. Is there such a revelation in the prior art? If ABCD and E have similar functions and the same structure, people in the field can easily think of E from ABCD, which is not creative. If ABCD and E are not comparable at all, they are not related. The word "infringement" you said is too big. If you only apply for a patent, you may be PASS off in the actual trial and you will not get a patent. Infringement means that you use the method to produce its products without the consent of the patentee, and then obtain economic benefits.
After your patent application, there are only two results, authorization or rejection. Authorization means that the products you protect are different, and there is no conflict of interest between you and him. You sell your products and he sells its products. If it is rejected, it means that your invention is not creative, and the product you invented has not been recognized, so the economic benefit should not be great.